Add '@since' Javadoc tag to all tracing APIs (issue #864).

This commit also adds missing Javadocs.

30 files changed, 632 insertions, 61 deletions

diff --git a/api/src/main/java/io/opencensus/trace/Annotation.java b/api/src/main/java/io/opencensus/trace/Annotation.java
index 3a893647..233968d3 100644
--- a/api/src/main/java/io/opencensus/trace/Annotation.java
+++ b/api/src/main/java/io/opencensus/trace/Annotation.java
@@ -24,7 +24,11 @@ import java.util.HashMap;
 import java.util.Map;
 import javax.annotation.concurrent.Immutable;
 
-/** A text annotation with a set of attributes. */
+/**
+ * A text annotation with a set of attributes.
+ *
+ * @since 0.5
+ */
 @Immutable
 @AutoValue
 // Suppress Checker Framework warning about missing @Nullable in generated equals method.
@@ -40,6 +44,7 @@ public abstract class Annotation {
    * @param description the text description of the {@code Annotation}.
    * @return a new {@code Annotation} with the given description.
    * @throws NullPointerException if {@code description} is {@code null}.
+   * @since 0.5
    */
   public static Annotation fromDescription(String description) {
     return new AutoValue_Annotation(description, EMPTY_ATTRIBUTES);
@@ -52,6 +57,7 @@ public abstract class Annotation {
    * @param attributes the attributes of the {@code Annotation}.
    * @return a new {@code Annotation} with the given description and set of attributes.
    * @throws NullPointerException if {@code description} or {@code attributes} are {@code null}.
+   * @since 0.5
    */
   public static Annotation fromDescriptionAndAttributes(
       String description, Map<String, AttributeValue> attributes) {
@@ -65,6 +71,7 @@ public abstract class Annotation {
    * Return the description of the {@code Annotation}.
    *
    * @return the description of the {@code Annotation}.
+   * @since 0.5
    */
   public abstract String getDescription();
 
@@ -72,6 +79,7 @@ public abstract class Annotation {
    * Return the attributes of the {@code Annotation}.
    *
    * @return the attributes of the {@code Annotation}.
+   * @since 0.5
    */
   public abstract Map<String, AttributeValue> getAttributes();
 
diff --git a/api/src/main/java/io/opencensus/trace/AttributeValue.java b/api/src/main/java/io/opencensus/trace/AttributeValue.java
index 6c938bd6..ed59830e 100644
--- a/api/src/main/java/io/opencensus/trace/AttributeValue.java
+++ b/api/src/main/java/io/opencensus/trace/AttributeValue.java
@@ -25,6 +25,8 @@ import javax.annotation.concurrent.Immutable;
 /**
  * A class that represents all the possible values for an attribute. An attribute can have 3 types
  * of values: {@code String}, {@code Boolean} or {@code Long}.
+ *
+ * @since 0.5
  */
 @Immutable
 public abstract class AttributeValue {
@@ -34,6 +36,7 @@ public abstract class AttributeValue {
    * @param stringValue The new value.
    * @return an {@code AttributeValue} with a string value.
    * @throws NullPointerException if {@code stringValue} is {@code null}.
+   * @since 0.5
    */
   public static AttributeValue stringAttributeValue(String stringValue) {
     return AttributeValueString.create(stringValue);
@@ -44,6 +47,7 @@ public abstract class AttributeValue {
    *
    * @param booleanValue The new value.
    * @return an {@code AttributeValue} with a boolean value.
+   * @since 0.5
    */
   public static AttributeValue booleanAttributeValue(boolean booleanValue) {
     return AttributeValueBoolean.create(booleanValue);
@@ -54,6 +58,7 @@ public abstract class AttributeValue {
    *
    * @param longValue The new value.
    * @return an {@code AttributeValue} with a long value.
+   * @since 0.5
    */
   public static AttributeValue longAttributeValue(long longValue) {
     return AttributeValueLong.create(longValue);
@@ -73,6 +78,7 @@ public abstract class AttributeValue {
    *     added after this {@code match} method was added to the API. See {@link
    *     io.opencensus.common.Functions} for some common functions for handling unknown types.
    * @return the result of the function applied to the underlying value.
+   * @since 0.5
    */
   public abstract <T> T match(
       Function<? super String, T> stringFunction,
diff --git a/api/src/main/java/io/opencensus/trace/BlankSpan.java b/api/src/main/java/io/opencensus/trace/BlankSpan.java
index 0c35a885..0f11a034 100644
--- a/api/src/main/java/io/opencensus/trace/BlankSpan.java
+++ b/api/src/main/java/io/opencensus/trace/BlankSpan.java
@@ -24,10 +24,16 @@ import javax.annotation.concurrent.Immutable;
  * no {@code Span} implementation is available. All operations are no-op.
  *
  * <p>Used also to stop tracing, see {@link Tracer#withSpan}.
+ *
+ * @since 0.5
  */
 @Immutable
 public final class BlankSpan extends Span {
-  /** Singleton instance of this class. */
+  /**
+   * Singleton instance of this class.
+   *
+   * @since 0.5
+   */
   public static final BlankSpan INSTANCE = new BlankSpan();
 
   private BlankSpan() {
diff --git a/api/src/main/java/io/opencensus/trace/EndSpanOptions.java b/api/src/main/java/io/opencensus/trace/EndSpanOptions.java
index 5c46e06f..d9e31e63 100644
--- a/api/src/main/java/io/opencensus/trace/EndSpanOptions.java
+++ b/api/src/main/java/io/opencensus/trace/EndSpanOptions.java
@@ -25,6 +25,8 @@ import javax.annotation.concurrent.Immutable;
 /**
  * A class that enables overriding the default values used when ending a {@link Span}. Allows
  * overriding the {@link Status status}.
+ *
+ * @since 0.5
  */
 @Immutable
 @AutoValue
@@ -32,13 +34,18 @@ import javax.annotation.concurrent.Immutable;
 @AutoValue.CopyAnnotations
 @SuppressWarnings("nullness")
 public abstract class EndSpanOptions {
-  /** The default {@code EndSpanOptions}. */
+  /**
+   * The default {@code EndSpanOptions}.
+   *
+   * @since 0.5
+   */
   public static final EndSpanOptions DEFAULT = builder().build();
 
   /**
    * Returns a new {@link Builder} with default options.
    *
    * @return a new {@code Builder} with default options.
+   * @since 0.5
    */
   public static Builder builder() {
     return new AutoValue_EndSpanOptions.Builder().setSampleToLocalSpanStore(false);
@@ -55,6 +62,7 @@ public abstract class EndSpanOptions {
    *
    * @return {@code true} if the name of the {@code Span} should be registered to the {@code
    *     io.opencensus.trace.export.SampledSpanStore}.
+   * @since 0.8
    */
   @ExperimentalApi
   public abstract boolean getSampleToLocalSpanStore();
@@ -66,11 +74,16 @@ public abstract class EndSpanOptions {
    * Span#setStatus(Status)} or the default {@link Status#OK} if no status was set.
    *
    * @return the status.
+   * @since 0.5
    */
   @Nullable
   public abstract Status getStatus();
 
-  /** Builder class for {@link EndSpanOptions}. */
+  /**
+   * Builder class for {@link EndSpanOptions}.
+   *
+   * @since 0.5
+   */
   @AutoValue.Builder
   public abstract static class Builder {
     /**
@@ -80,6 +93,7 @@ public abstract class EndSpanOptions {
      *
      * @param status the status.
      * @return this.
+     * @since 0.5
      */
     public abstract Builder setStatus(Status status);
 
@@ -96,6 +110,7 @@ public abstract class EndSpanOptions {
      * instead.
      *
      * @return this.
+     * @since 0.8
      */
     @ExperimentalApi
     public abstract Builder setSampleToLocalSpanStore(boolean sampleToLocalSpanStore);
@@ -104,6 +119,7 @@ public abstract class EndSpanOptions {
      * Builds and returns a {@code EndSpanOptions} with the desired settings.
      *
      * @return a {@code EndSpanOptions} with the desired settings.
+     * @since 0.5
      */
     public abstract EndSpanOptions build();
 
diff --git a/api/src/main/java/io/opencensus/trace/Link.java b/api/src/main/java/io/opencensus/trace/Link.java
index 77b17206..e877a010 100644
--- a/api/src/main/java/io/opencensus/trace/Link.java
+++ b/api/src/main/java/io/opencensus/trace/Link.java
@@ -30,6 +30,8 @@ import javax.annotation.concurrent.Immutable;
  *
  * <p>Used (for example) in batching operations, where a single batch handler processes multiple
  * requests from different traces.
+ *
+ * @since 0.5
  */
 @Immutable
 @AutoValue
@@ -39,11 +41,23 @@ import javax.annotation.concurrent.Immutable;
 public abstract class Link {
   private static final Map<String, AttributeValue> EMPTY_ATTRIBUTES = Collections.emptyMap();
 
-  /** The relationship with the linked {@code Span} relative to the current {@code Span}. */
+  /**
+   * The relationship with the linked {@code Span} relative to the current {@code Span}.
+   *
+   * @since 0.5
+   */
   public enum Type {
-    /** When the linked {@code Span} is a child of the current {@code Span}. */
+    /**
+     * When the linked {@code Span} is a child of the current {@code Span}.
+     *
+     * @since 0.5
+     */
     CHILD_LINKED_SPAN,
-    /** When the linked {@code Span} is a parent of the current {@code Span}. */
+    /**
+     * When the linked {@code Span} is a parent of the current {@code Span}.
+     *
+     * @since 0.5
+     */
     PARENT_LINKED_SPAN
   }
 
@@ -53,6 +67,7 @@ public abstract class Link {
    * @param context the context of the linked {@code Span}.
    * @param type the type of the relationship with the linked {@code Span}.
    * @return a new {@code Link}.
+   * @since 0.5
    */
   public static Link fromSpanContext(SpanContext context, Type type) {
     return new AutoValue_Link(context.getTraceId(), context.getSpanId(), type, EMPTY_ATTRIBUTES);
@@ -65,6 +80,7 @@ public abstract class Link {
    * @param type the type of the relationship with the linked {@code Span}.
    * @param attributes the attributes of the {@code Link}.
    * @return a new {@code Link}.
+   * @since 0.5
    */
   public static Link fromSpanContext(
       SpanContext context, Type type, Map<String, AttributeValue> attributes) {
@@ -79,6 +95,7 @@ public abstract class Link {
    * Returns the {@code TraceId}.
    *
    * @return the {@code TraceId}.
+   * @since 0.5
    */
   public abstract TraceId getTraceId();
 
@@ -86,6 +103,7 @@ public abstract class Link {
    * Returns the {@code SpanId}.
    *
    * @return the {@code SpanId}
+   * @since 0.5
    */
   public abstract SpanId getSpanId();
 
@@ -93,6 +111,7 @@ public abstract class Link {
    * Returns the {@code Type}.
    *
    * @return the {@code Type}.
+   * @since 0.5
    */
   public abstract Type getType();
 
@@ -100,6 +119,7 @@ public abstract class Link {
    * Returns the set of attributes.
    *
    * @return the set of attributes.
+   * @since 0.5
    */
   public abstract Map<String, AttributeValue> getAttributes();
 
diff --git a/api/src/main/java/io/opencensus/trace/NetworkEvent.java b/api/src/main/java/io/opencensus/trace/NetworkEvent.java
index a38bbdb8..a8dfdb70 100644
--- a/api/src/main/java/io/opencensus/trace/NetworkEvent.java
+++ b/api/src/main/java/io/opencensus/trace/NetworkEvent.java
@@ -27,6 +27,8 @@ import javax.annotation.concurrent.Immutable;
  * A class that represents a network event. It requires a {@link Type type} and a message id that
  * serves to uniquely identify each network message. It can optionally can have information about
  * the kernel time and message size.
+ *
+ * @since 0.5
  */
 @Immutable
 @AutoValue
@@ -34,11 +36,23 @@ import javax.annotation.concurrent.Immutable;
 @AutoValue.CopyAnnotations
 @SuppressWarnings("nullness")
 public abstract class NetworkEvent {
-  /** Available types for a {@code NetworkEvent}. */
+  /**
+   * Available types for a {@code NetworkEvent}.
+   *
+   * @since 0.5
+   */
   public enum Type {
-    /** When the message was sent. */
+    /**
+     * When the message was sent.
+     *
+     * @since 0.5
+     */
     SENT,
-    /** When the message was received. */
+    /**
+     * When the message was received.
+     *
+     * @since 0.5
+     */
     RECV,
   }
 
@@ -49,6 +63,7 @@ public abstract class NetworkEvent {
    * @param messageId serves to uniquely identify each network message.
    * @return a new {@code Builder} with default values.
    * @throws NullPointerException if {@code type} is {@code null}.
+   * @since 0.5
    */
   public static Builder builder(Type type, long messageId) {
     return new AutoValue_NetworkEvent.Builder()
@@ -66,6 +81,7 @@ public abstract class NetworkEvent {
    *
    * @return the kernel timestamp associated with the {@code NetworkEvent} or {@code null} if not
    *     set.
+   * @since 0.5
    */
   @Nullable
   public abstract Timestamp getKernelTimestamp();
@@ -74,6 +90,7 @@ public abstract class NetworkEvent {
    * Returns the type of the {@code NetworkEvent}.
    *
    * @return the type of the {@code NetworkEvent}.
+   * @since 0.5
    */
   public abstract Type getType();
 
@@ -81,6 +98,7 @@ public abstract class NetworkEvent {
    * Returns the message id argument that serves to uniquely identify each network message.
    *
    * @return the message id of the {@code NetworkEvent}.
+   * @since 0.5
    */
   public abstract long getMessageId();
 
@@ -88,6 +106,7 @@ public abstract class NetworkEvent {
    * Returns the uncompressed size in bytes of the {@code NetworkEvent}.
    *
    * @return the uncompressed size in bytes of the {@code NetworkEvent}.
+   * @since 0.6
    */
   public abstract long getUncompressedMessageSize();
 
@@ -95,19 +114,25 @@ public abstract class NetworkEvent {
    * Returns the compressed size in bytes of the {@code NetworkEvent}.
    *
    * @return the compressed size in bytes of the {@code NetworkEvent}.
+   * @since 0.6
    */
   public abstract long getCompressedMessageSize();
 
   /**
    * @deprecated Use {@link #getUncompressedMessageSize}.
    * @return the uncompressed size in bytes of the {@code NetworkEvent}.
+   * @since 0.5
    */
   @Deprecated
   public long getMessageSize() {
     return getUncompressedMessageSize();
   }
 
-  /** Builder class for {@link NetworkEvent}. */
+  /**
+   * Builder class for {@link NetworkEvent}.
+   *
+   * @since 0.5
+   */
   @AutoValue.Builder
   public abstract static class Builder {
     // Package protected methods because these values are mandatory and set only in the
@@ -121,6 +146,7 @@ public abstract class NetworkEvent {
      *
      * @param kernelTimestamp The kernel timestamp of the event.
      * @return this.
+     * @since 0.5
      */
     public abstract Builder setKernelTimestamp(@Nullable Timestamp kernelTimestamp);
 
@@ -128,6 +154,7 @@ public abstract class NetworkEvent {
      * @deprecated Use {@link #setUncompressedMessageSize}.
      * @param messageSize represents the uncompressed size in bytes of this message.
      * @return this.
+     * @since 0.5
      */
     @Deprecated
     public Builder setMessageSize(long messageSize) {
@@ -139,6 +166,7 @@ public abstract class NetworkEvent {
      *
      * @param uncompressedMessageSize represents the uncompressed size in bytes of this message.
      * @return this.
+     * @since 0.6
      */
     public abstract Builder setUncompressedMessageSize(long uncompressedMessageSize);
 
@@ -147,6 +175,7 @@ public abstract class NetworkEvent {
      *
      * @param compressedMessageSize represents the compressed size in bytes of this message.
      * @return this.
+     * @since 0.6
      */
     public abstract Builder setCompressedMessageSize(long compressedMessageSize);
 
@@ -154,6 +183,7 @@ public abstract class NetworkEvent {
      * Builds and returns a {@code NetworkEvent} with the desired values.
      *
      * @return a {@code NetworkEvent} with the desired values.
+     * @since 0.5
      */
     public abstract NetworkEvent build();
 
diff --git a/api/src/main/java/io/opencensus/trace/Sampler.java b/api/src/main/java/io/opencensus/trace/Sampler.java
index e30b5fdd..e89af89b 100644
--- a/api/src/main/java/io/opencensus/trace/Sampler.java
+++ b/api/src/main/java/io/opencensus/trace/Sampler.java
@@ -19,7 +19,11 @@ package io.opencensus.trace;
 import java.util.List;
 import javax.annotation.Nullable;
 
-/** Sampler is used to make decisions on {@link Span} sampling. */
+/**
+ * Sampler is used to make decisions on {@link Span} sampling.
+ *
+ * @since 0.5
+ */
 public abstract class Sampler {
   /**
    * Called during {@link Span} creation to make a sampling decision.
@@ -34,6 +38,7 @@ public abstract class Sampler {
    * @param name the name of the new {@code Span}.
    * @param parentLinks the parentLinks associated with the new {@code Span}.
    * @return {@code true} if the {@code Span} is sampled.
+   * @since 0.5
    */
   public abstract boolean shouldSample(
       @Nullable SpanContext parentContext,
@@ -50,6 +55,7 @@ public abstract class Sampler {
    * <p>Example: "ProbabilitySampler{0.000100}"
    *
    * @return the description of this {@code Sampler}.
+   * @since 0.6
    */
   public abstract String getDescription();
 }
diff --git a/api/src/main/java/io/opencensus/trace/Span.java b/api/src/main/java/io/opencensus/trace/Span.java
index 16aac33f..29673930 100644
--- a/api/src/main/java/io/opencensus/trace/Span.java
+++ b/api/src/main/java/io/opencensus/trace/Span.java
@@ -32,6 +32,8 @@ import javax.annotation.Nullable;
  * <p>Spans are created by the {@link SpanBuilder#startSpan} method.
  *
  * <p>{@code Span} <b>must</b> be ended by calling {@link #end()} or {@link #end(EndSpanOptions)}
+ *
+ * @since 0.5
  */
 public abstract class Span {
   private static final Map<String, AttributeValue> EMPTY_ATTRIBUTES = Collections.emptyMap();
@@ -45,11 +47,15 @@ public abstract class Span {
   /**
    * {@code Span} options. These options are NOT propagated to child spans. These options determine
    * features such as whether a {@code Span} should record any annotations or events.
+   *
+   * @since 0.5
    */
   public enum Options {
     /**
      * This option is set if the Span is part of a sampled distributed trace OR {@link
      * SpanBuilder#setRecordEvents(boolean)} was called with true.
+     *
+     * @since 0.5
      */
     RECORD_EVENTS;
   }
@@ -66,6 +72,7 @@ public abstract class Span {
    * @throws NullPointerException if context is {@code null}.
    * @throws IllegalArgumentException if the {@code SpanContext} is sampled but no RECORD_EVENTS
    *     options.
+   * @since 0.5
    */
   protected Span(SpanContext context, @Nullable EnumSet<Options> options) {
     this.context = checkNotNull(context, "context");
@@ -84,6 +91,7 @@ public abstract class Span {
    *
    * @param key the key for this attribute.
    * @param value the value for this attribute.
+   * @since 0.6
    */
   public void putAttribute(String key, AttributeValue value) {
     // Not final because for performance reasons we want to override this in the implementation.
@@ -98,6 +106,7 @@ public abstract class Span {
    * map.
    *
    * @param attributes the attributes that will be added and associated with the {@code Span}.
+   * @since 0.6
    */
   public void putAttributes(Map<String, AttributeValue> attributes) {
     // Not final because we want to start overriding this method from the beginning, this will
@@ -108,6 +117,7 @@ public abstract class Span {
   /**
    * @deprecated Use {@link #putAttributes(Map)}
    * @param attributes the attributes that will be added and associated with the {@code Span}.
+   * @since 0.5
    */
   @Deprecated
   public void addAttributes(Map<String, AttributeValue> attributes) {
@@ -118,6 +128,7 @@ public abstract class Span {
    * Adds an annotation to the {@code Span}.
    *
    * @param description the description of the annotation time event.
+   * @since 0.5
    */
   public final void addAnnotation(String description) {
     addAnnotation(description, EMPTY_ATTRIBUTES);
@@ -129,6 +140,7 @@ public abstract class Span {
    * @param description the description of the annotation time event.
    * @param attributes the attributes that will be added; these are associated with this annotation,
    *     not the {@code Span} as for {@link #putAttributes(Map)}.
+   * @since 0.5
    */
   public abstract void addAnnotation(String description, Map<String, AttributeValue> attributes);
 
@@ -136,6 +148,7 @@ public abstract class Span {
    * Adds an annotation to the {@code Span}.
    *
    * @param annotation the annotations to add.
+   * @since 0.5
    */
   public abstract void addAnnotation(Annotation annotation);
 
@@ -146,6 +159,7 @@ public abstract class Span {
    * higher level applications.
    *
    * @param networkEvent the network event to add.
+   * @since 0.5
    */
   public abstract void addNetworkEvent(NetworkEvent networkEvent);
 
@@ -156,6 +170,7 @@ public abstract class Span {
    * requests from different traces.
    *
    * @param link the link to add.
+   * @since 0.5
    */
   public abstract void addLink(Link link);
 
@@ -169,6 +184,7 @@ public abstract class Span {
    * will always be the last call.
    *
    * @param status the {@link Status} to set.
+   * @since 0.9
    */
   public void setStatus(Status status) {
     // Implemented as no-op for backwards compatibility (for example gRPC extends Span in tests).
@@ -182,6 +198,7 @@ public abstract class Span {
    * implementations are free to ignore all further calls.
    *
    * @param options the options to be used for the end of the {@code Span}.
+   * @since 0.5
    */
   public abstract void end(EndSpanOptions options);
 
@@ -190,6 +207,8 @@ public abstract class Span {
    *
    * <p>Only the timing of the first end call for a given {@code Span} will be recorded, and
    * implementations are free to ignore all further calls.
+   *
+   * @since 0.5
    */
   public final void end() {
     end(EndSpanOptions.DEFAULT);
@@ -199,6 +218,7 @@ public abstract class Span {
    * Returns the {@code SpanContext} associated with this {@code Span}.
    *
    * @return the {@code SpanContext} associated with this {@code Span}.
+   * @since 0.5
    */
   public final SpanContext getContext() {
     return context;
@@ -208,6 +228,7 @@ public abstract class Span {
    * Returns the options associated with this {@code Span}.
    *
    * @return the options associated with this {@code Span}.
+   * @since 0.5
    */
   public final Set<Options> getOptions() {
     return options;
diff --git a/api/src/main/java/io/opencensus/trace/SpanBuilder.java b/api/src/main/java/io/opencensus/trace/SpanBuilder.java
index 04c339ff..ee68d109 100644
--- a/api/src/main/java/io/opencensus/trace/SpanBuilder.java
+++ b/api/src/main/java/io/opencensus/trace/SpanBuilder.java
@@ -104,6 +104,8 @@ import javax.annotation.Nullable;
  *
  * <p>If your Java version is less than Java SE 7, see {@link SpanBuilder#startSpan} and {@link
  * SpanBuilder#startScopedSpan} for usage examples.
+ *
+ * @since 0.5
  */
 public abstract class SpanBuilder {
 
@@ -112,6 +114,7 @@ public abstract class SpanBuilder {
    *
    * @param sampler The {@code Sampler} to use when determining sampling for a {@code Span}.
    * @return this.
+   * @since 0.5
    */
   public abstract SpanBuilder setSampler(Sampler sampler);
 
@@ -123,6 +126,7 @@ public abstract class SpanBuilder {
    * @param parentLinks New links to be added.
    * @return this.
    * @throws NullPointerException if {@code parentLinks} is {@code null}.
+   * @since 0.5
    */
   public abstract SpanBuilder setParentLinks(List<Span> parentLinks);
 
@@ -132,6 +136,7 @@ public abstract class SpanBuilder {
    *
    * @param recordEvents New value determining if this {@code Span} should have events recorded.
    * @return this.
+   * @since 0.5
    */
   public abstract SpanBuilder setRecordEvents(boolean recordEvents);
 
@@ -162,6 +167,7 @@ public abstract class SpanBuilder {
    * }</pre>
    *
    * @return the newly created {@code Span}.
+   * @since 0.5
    */
   public abstract Span startSpan();
 
@@ -218,6 +224,7 @@ public abstract class SpanBuilder {
    *
    * @return an object that defines a scope where the newly created {@code Span} will be set to the
    *     current Context.
+   * @since 0.5
    */
   @MustBeClosed
   public final Scope startScopedSpan() {
diff --git a/api/src/main/java/io/opencensus/trace/SpanContext.java b/api/src/main/java/io/opencensus/trace/SpanContext.java
index 6084c674..cdc74886 100644
--- a/api/src/main/java/io/opencensus/trace/SpanContext.java
+++ b/api/src/main/java/io/opencensus/trace/SpanContext.java
@@ -26,6 +26,8 @@ import javax.annotation.concurrent.Immutable;
  * child {@link Span}s and across process boundaries. It contains the identifiers (a {@link TraceId
  * trace_id} and {@link SpanId span_id}) associated with the {@link Span} and a set of {@link
  * TraceOptions options}.
+ *
+ * @since 0.5
  */
 @Immutable
 public final class SpanContext {
@@ -33,7 +35,11 @@ public final class SpanContext {
   private final SpanId spanId;
   private final TraceOptions traceOptions;
 
-  /** The invalid {@code SpanContext}. */
+  /**
+   * The invalid {@code SpanContext}.
+   *
+   * @since 0.5
+   */
   public static final SpanContext INVALID =
       new SpanContext(TraceId.INVALID, SpanId.INVALID, TraceOptions.DEFAULT);
 
@@ -44,6 +50,7 @@ public final class SpanContext {
    * @param spanId the span identifier of the span context.
    * @param traceOptions the trace options for the span context.
    * @return a new {@code SpanContext} with the given identifiers and options.
+   * @since 0.5
    */
   public static SpanContext create(TraceId traceId, SpanId spanId, TraceOptions traceOptions) {
     return new SpanContext(traceId, spanId, traceOptions);
@@ -53,6 +60,7 @@ public final class SpanContext {
    * Returns the trace identifier associated with this {@code SpanContext}.
    *
    * @return the trace identifier associated with this {@code SpanContext}.
+   * @since 0.5
    */
   public TraceId getTraceId() {
     return traceId;
@@ -62,6 +70,7 @@ public final class SpanContext {
    * Returns the span identifier associated with this {@code SpanContext}.
    *
    * @return the span identifier associated with this {@code SpanContext}.
+   * @since 0.5
    */
   public SpanId getSpanId() {
     return spanId;
@@ -71,6 +80,7 @@ public final class SpanContext {
    * Returns the trace options associated with this {@code SpanContext}.
    *
    * @return the trace options associated with this {@code SpanContext}.
+   * @since 0.5
    */
   public TraceOptions getTraceOptions() {
     return traceOptions;
@@ -80,6 +90,7 @@ public final class SpanContext {
    * Returns true if this {@code SpanContext} is valid.
    *
    * @return true if this {@code SpanContext} is valid.
+   * @since 0.5
    */
   public boolean isValid() {
     return traceId.isValid() && spanId.isValid();
diff --git a/api/src/main/java/io/opencensus/trace/SpanId.java b/api/src/main/java/io/opencensus/trace/SpanId.java
index 76747acf..eee5f497 100644
--- a/api/src/main/java/io/opencensus/trace/SpanId.java
+++ b/api/src/main/java/io/opencensus/trace/SpanId.java
@@ -29,13 +29,23 @@ import javax.annotation.concurrent.Immutable;
 /**
  * A class that represents a span identifier. A valid span identifier is an 8-byte array with at
  * least one non-zero byte.
+ *
+ * @since 0.5
  */
 @Immutable
 public final class SpanId implements Comparable<SpanId> {
-  /** The size in bytes of the {@code SpanId}. */
+  /**
+   * The size in bytes of the {@code SpanId}.
+   *
+   * @since 0.5
+   */
   public static final int SIZE = 8;
 
-  /** The invalid {@code SpanId}. All bytes are 0. */
+  /**
+   * The invalid {@code SpanId}. All bytes are 0.
+   *
+   * @since 0.5
+   */
   public static final SpanId INVALID = new SpanId(new byte[SIZE]);
 
   // The internal representation of the SpanId.
@@ -58,6 +68,7 @@ public final class SpanId implements Comparable<SpanId> {
    * @return a {@code SpanId} whose representation is given by the {@code buffer} parameter.
    * @throws NullPointerException if {@code buffer} is null.
    * @throws IllegalArgumentException if {@code buffer.length} is not {@link SpanId#SIZE}.
+   * @since 0.5
    */
   public static SpanId fromBytes(byte[] buffer) {
     checkNotNull(buffer, "buffer");
@@ -77,6 +88,7 @@ public final class SpanId implements Comparable<SpanId> {
    * @throws NullPointerException if {@code src} is null.
    * @throws IndexOutOfBoundsException if {@code srcOffset+SpanId.SIZE} is greater than {@code
    *     src.length}.
+   * @since 0.5
    */
   public static SpanId fromBytes(byte[] src, int srcOffset) {
     byte[] bytes = new byte[SIZE];
@@ -92,6 +104,7 @@ public final class SpanId implements Comparable<SpanId> {
    * @throws NullPointerException if {@code src} is null.
    * @throws IllegalArgumentException if {@code src.length} is not {@code 2 * SpanId.SIZE} OR if the
    *     {@code str} has invalid characters.
+   * @since 0.11
    */
   public static SpanId fromLowerBase16(CharSequence src) {
     checkArgument(
@@ -105,6 +118,7 @@ public final class SpanId implements Comparable<SpanId> {
    *
    * @param random The random number generator.
    * @return a valid new {@code SpanId}.
+   * @since 0.5
    */
   public static SpanId generateRandomId(Random random) {
     byte[] bytes = new byte[SIZE];
@@ -118,6 +132,7 @@ public final class SpanId implements Comparable<SpanId> {
    * Returns the byte representation of the {@code SpanId}.
    *
    * @return the byte representation of the {@code SpanId}.
+   * @since 0.5
    */
   public byte[] getBytes() {
     return Arrays.copyOf(bytes, SIZE);
@@ -138,6 +153,7 @@ public final class SpanId implements Comparable<SpanId> {
    * @throws NullPointerException if {@code dest} is null.
    * @throws IndexOutOfBoundsException if {@code destOffset+SpanId.SIZE} is greater than {@code
    *     dest.length}.
+   * @since 0.5
    */
   public void copyBytesTo(byte[] dest, int destOffset) {
     System.arraycopy(bytes, 0, dest, destOffset, SIZE);
@@ -148,6 +164,7 @@ public final class SpanId implements Comparable<SpanId> {
    * at least one non-zero byte.
    *
    * @return {@code true} if the span identifier is valid.
+   * @since 0.5
    */
   public boolean isValid() {
     return !Arrays.equals(bytes, INVALID.bytes);
@@ -157,6 +174,7 @@ public final class SpanId implements Comparable<SpanId> {
    * Returns the lowercase base16 encoding of this {@code SpanId}.
    *
    * @return the lowercase base16 encoding of this {@code SpanId}.
+   * @since 0.11
    */
   public String toLowerBase16() {
     return BaseEncoding.base16().lowerCase().encode(bytes);
diff --git a/api/src/main/java/io/opencensus/trace/Status.java b/api/src/main/java/io/opencensus/trace/Status.java
index f5a275bf..b8c6b7a1 100644
--- a/api/src/main/java/io/opencensus/trace/Status.java
+++ b/api/src/main/java/io/opencensus/trace/Status.java
@@ -38,18 +38,30 @@ import org.checkerframework.dataflow.qual.Deterministic;
  * the template for the appropriate {@link Status.CanonicalCode} and supplementing it with
  * additional information: {@code Status.NOT_FOUND.withDescription("Could not find
  * 'important_file.txt'");}
+ *
+ * @since 0.5
  */
 @Immutable
 public final class Status {
   /**
    * The set of canonical status codes. If new codes are added over time they must choose a
    * numerical value that does not collide with any previously used value.
+   *
+   * @since 0.5
    */
   public enum CanonicalCode {
-    /** The operation completed successfully. */
+    /**
+     * The operation completed successfully.
+     *
+     * @since 0.5
+     */
     OK(0),
 
-    /** The operation was cancelled (typically by the caller). */
+    /**
+     * The operation was cancelled (typically by the caller).
+     *
+     * @since 0.5
+     */
     CANCELLED(1),
 
     /**
@@ -57,6 +69,8 @@ public final class Status {
      * from another address space belongs to an error-space that is not known in this address space.
      * Also errors raised by APIs that do not return enough error information may be converted to
      * this error.
+     *
+     * @since 0.5
      */
     UNKNOWN(2),
 
@@ -64,6 +78,8 @@ public final class Status {
      * Client specified an invalid argument. Note that this differs from FAILED_PRECONDITION.
      * INVALID_ARGUMENT indicates arguments that are problematic regardless of the state of the
      * system (e.g., a malformed file name).
+     *
+     * @since 0.5
      */
     INVALID_ARGUMENT(3),
 
@@ -72,13 +88,23 @@ public final class Status {
      * system, this error may be returned even if the operation has completed successfully. For
      * example, a successful response from a server could have been delayed long enough for the
      * deadline to expire.
+     *
+     * @since 0.5
      */
     DEADLINE_EXCEEDED(4),
 
-    /** Some requested entity (e.g., file or directory) was not found. */
+    /**
+     * Some requested entity (e.g., file or directory) was not found.
+     *
+     * @since 0.5
+     */
     NOT_FOUND(5),
 
-    /** Some entity that we attempted to create (e.g., file or directory) already exists. */
+    /**
+     * Some entity that we attempted to create (e.g., file or directory) already exists.
+     *
+     * @since 0.5
+     */
     ALREADY_EXISTS(6),
 
     /**
@@ -86,12 +112,16 @@ public final class Status {
      * must not be used for rejections caused by exhausting some resource (use RESOURCE_EXHAUSTED
      * instead for those errors). PERMISSION_DENIED must not be used if the caller cannot be
      * identified (use UNAUTHENTICATED instead for those errors).
+     *
+     * @since 0.5
      */
     PERMISSION_DENIED(7),
 
     /**
      * Some resource has been exhausted, perhaps a per-user quota, or perhaps the entire file system
      * is out of space.
+     *
+     * @since 0.5
      */
     RESOURCE_EXHAUSTED(8),
 
@@ -107,6 +137,8 @@ public final class Status {
      * the system state has been explicitly fixed. E.g., if an "rmdir" fails because the directory
      * is non-empty, FAILED_PRECONDITION should be returned since the client should not retry unless
      * they have first fixed up the directory by deleting files from it.
+     *
+     * @since 0.5
      */
     FAILED_PRECONDITION(9),
 
@@ -115,6 +147,8 @@ public final class Status {
      * failures, transaction aborts, etc.
      *
      * <p>See litmus test above for deciding between FAILED_PRECONDITION, ABORTED, and UNAVAILABLE.
+     *
+     * @since 0.5
      */
     ABORTED(10),
 
@@ -130,15 +164,23 @@ public final class Status {
      * using OUT_OF_RANGE (the more specific error) when it applies so that callers who are
      * iterating through a space can easily look for an OUT_OF_RANGE error to detect when they are
      * done.
+     *
+     * @since 0.5
      */
     OUT_OF_RANGE(11),
 
-    /** Operation is not implemented or not supported/enabled in this service. */
+    /**
+     * Operation is not implemented or not supported/enabled in this service.
+     *
+     * @since 0.5
+     */
     UNIMPLEMENTED(12),
 
     /**
      * Internal errors. Means some invariants expected by underlying system has been broken. If you
      * see one of these errors, something is very broken.
+     *
+     * @since 0.5
      */
     INTERNAL(13),
 
@@ -147,13 +189,23 @@ public final class Status {
      * corrected by retrying with a backoff.
      *
      * <p>See litmus test above for deciding between FAILED_PRECONDITION, ABORTED, and UNAVAILABLE.
+     *
+     * @since 0.5
      */
     UNAVAILABLE(14),
 
-    /** Unrecoverable data loss or corruption. */
+    /**
+     * Unrecoverable data loss or corruption.
+     *
+     * @since 0.5
+     */
     DATA_LOSS(15),
 
-    /** The request does not have valid authentication credentials for the operation. */
+    /**
+     * The request does not have valid authentication credentials for the operation.
+     *
+     * @since 0.5
+     */
     UNAUTHENTICATED(16);
 
     private final int value;
@@ -166,6 +218,7 @@ public final class Status {
      * Returns the numerical value of the code.
      *
      * @return the numerical value of the code.
+     * @since 0.5
      */
     public int value() {
       return value;
@@ -175,6 +228,7 @@ public final class Status {
      * Returns the status that has the current {@code CanonicalCode}..
      *
      * @return the status that has the current {@code CanonicalCode}.
+     * @since 0.5
      */
     @VisibleForTesting
     public Status toStatus() {
@@ -202,53 +256,127 @@ public final class Status {
 
   // A pseudo-enum of Status instances mapped 1:1 with values in CanonicalCode. This simplifies
   // construction patterns for derived instances of Status.
-  /** The operation completed successfully. */
+  /**
+   * The operation completed successfully.
+   *
+   * @since 0.5
+   */
   public static final Status OK = CanonicalCode.OK.toStatus();
-  /** The operation was cancelled (typically by the caller). */
+
+  /**
+   * The operation was cancelled (typically by the caller).
+   *
+   * @since 0.5
+   */
   public static final Status CANCELLED = CanonicalCode.CANCELLED.toStatus();
-  /** Unknown error. See {@link CanonicalCode#UNKNOWN}. */
+
+  /**
+   * Unknown error. See {@link CanonicalCode#UNKNOWN}.
+   *
+   * @since 0.5
+   */
   public static final Status UNKNOWN = CanonicalCode.UNKNOWN.toStatus();
-  /** Client specified an invalid argument. See {@link CanonicalCode#INVALID_ARGUMENT}. */
+
+  /**
+   * Client specified an invalid argument. See {@link CanonicalCode#INVALID_ARGUMENT}.
+   *
+   * @since 0.5
+   */
   public static final Status INVALID_ARGUMENT = CanonicalCode.INVALID_ARGUMENT.toStatus();
+
   /**
    * Deadline expired before operation could complete. See {@link CanonicalCode#DEADLINE_EXCEEDED}.
+   *
+   * @since 0.5
    */
   public static final Status DEADLINE_EXCEEDED = CanonicalCode.DEADLINE_EXCEEDED.toStatus();
-  /** Some requested entity (e.g., file or directory) was not found. */
+
+  /**
+   * Some requested entity (e.g., file or directory) was not found.
+   *
+   * @since 0.5
+   */
   public static final Status NOT_FOUND = CanonicalCode.NOT_FOUND.toStatus();
-  /** Some entity that we attempted to create (e.g., file or directory) already exists. */
+
+  /**
+   * Some entity that we attempted to create (e.g., file or directory) already exists.
+   *
+   * @since 0.5
+   */
   public static final Status ALREADY_EXISTS = CanonicalCode.ALREADY_EXISTS.toStatus();
+
   /**
    * The caller does not have permission to execute the specified operation. See {@link
    * CanonicalCode#PERMISSION_DENIED}.
+   *
+   * @since 0.5
    */
   public static final Status PERMISSION_DENIED = CanonicalCode.PERMISSION_DENIED.toStatus();
-  /** The request does not have valid authentication credentials for the operation. */
+
+  /**
+   * The request does not have valid authentication credentials for the operation.
+   *
+   * @since 0.5
+   */
   public static final Status UNAUTHENTICATED = CanonicalCode.UNAUTHENTICATED.toStatus();
+
   /**
    * Some resource has been exhausted, perhaps a per-user quota, or perhaps the entire file system
    * is out of space.
+   *
+   * @since 0.5
    */
   public static final Status RESOURCE_EXHAUSTED = CanonicalCode.RESOURCE_EXHAUSTED.toStatus();
+
   /**
    * Operation was rejected because the system is not in a state required for the operation's
    * execution. See {@link CanonicalCode#FAILED_PRECONDITION}.
+   *
+   * @since 0.5
    */
   public static final Status FAILED_PRECONDITION = CanonicalCode.FAILED_PRECONDITION.toStatus();
+
   /**
    * The operation was aborted, typically due to a concurrency issue like sequencer check failures,
    * transaction aborts, etc. See {@link CanonicalCode#ABORTED}.
+   *
+   * @since 0.5
    */
   public static final Status ABORTED = CanonicalCode.ABORTED.toStatus();
-  /** Operation was attempted past the valid range. See {@link CanonicalCode#OUT_OF_RANGE}. */
+
+  /**
+   * Operation was attempted past the valid range. See {@link CanonicalCode#OUT_OF_RANGE}.
+   *
+   * @since 0.5
+   */
   public static final Status OUT_OF_RANGE = CanonicalCode.OUT_OF_RANGE.toStatus();
-  /** Operation is not implemented or not supported/enabled in this service. */
+
+  /**
+   * Operation is not implemented or not supported/enabled in this service.
+   *
+   * @since 0.5
+   */
   public static final Status UNIMPLEMENTED = CanonicalCode.UNIMPLEMENTED.toStatus();
-  /** Internal errors. See {@link CanonicalCode#INTERNAL}. */
+
+  /**
+   * Internal errors. See {@link CanonicalCode#INTERNAL}.
+   *
+   * @since 0.5
+   */
   public static final Status INTERNAL = CanonicalCode.INTERNAL.toStatus();
-  /** The service is currently unavailable. See {@link CanonicalCode#UNAVAILABLE}. */
+
+  /**
+   * The service is currently unavailable. See {@link CanonicalCode#UNAVAILABLE}.
+   *
+   * @since 0.5
+   */
   public static final Status UNAVAILABLE = CanonicalCode.UNAVAILABLE.toStatus();
-  /** Unrecoverable data loss or corruption. */
+
+  /**
+   * Unrecoverable data loss or corruption.
+   *
+   * @since 0.5
+   */
   public static final Status DATA_LOSS = CanonicalCode.DATA_LOSS.toStatus();
 
   // The canonical code of this message.
@@ -267,6 +395,7 @@ public final class Status {
    *
    * @param description the new description of the {@code Status}.
    * @return The newly created {@code Status} with the given description.
+   * @since 0.5
    */
   public Status withDescription(String description) {
     if (Objects.equal(this.description, description)) {
@@ -279,6 +408,7 @@ public final class Status {
    * Returns the canonical status code.
    *
    * @return the canonical status code.
+   * @since 0.5
    */
   public CanonicalCode getCanonicalCode() {
     return canonicalCode;
@@ -288,6 +418,7 @@ public final class Status {
    * Returns the description of this {@code Status} for human consumption.
    *
    * @return the description of this {@code Status}.
+   * @since 0.5
    */
   @Nullable
   /*@Deterministic*/
@@ -299,6 +430,7 @@ public final class Status {
    * Returns {@code true} if this {@code Status} is OK, i.e., not an error.
    *
    * @return {@code true} if this {@code Status} is OK.
+   * @since 0.5
    */
   public boolean isOk() {
     return CanonicalCode.OK == canonicalCode;
diff --git a/api/src/main/java/io/opencensus/trace/TraceComponent.java b/api/src/main/java/io/opencensus/trace/TraceComponent.java
index a781f045..d98d0f9e 100644
--- a/api/src/main/java/io/opencensus/trace/TraceComponent.java
+++ b/api/src/main/java/io/opencensus/trace/TraceComponent.java
@@ -27,6 +27,8 @@ import io.opencensus.trace.propagation.PropagationComponent;
  * {@link Clock}, {@link ExportComponent} and {@link TraceConfig}.
  *
  * <p>Unless otherwise noted all methods (on component) results are cacheable.
+ *
+ * @since 0.5
  */
 public abstract class TraceComponent {
 
@@ -35,6 +37,7 @@ public abstract class TraceComponent {
    * then no-op implementations will be used.
    *
    * @return the {@code Tracer} implementation.
+   * @since 0.5
    */
   public abstract Tracer getTracer();
 
@@ -43,6 +46,7 @@ public abstract class TraceComponent {
    * is provided then no-op implementation will be used.
    *
    * @return the {@code PropagationComponent} implementation.
+   * @since 0.5
    */
   public abstract PropagationComponent getPropagationComponent();
 
@@ -50,6 +54,7 @@ public abstract class TraceComponent {
    * Returns the {@link Clock} with the provided implementation.
    *
    * @return the {@code Clock} implementation.
+   * @since 0.5
    */
   public abstract Clock getClock();
 
@@ -58,6 +63,7 @@ public abstract class TraceComponent {
    * provided then no-op implementations will be used.
    *
    * @return the {@link ExportComponent} implementation.
+   * @since 0.5
    */
   public abstract ExportComponent getExportComponent();
 
@@ -66,6 +72,7 @@ public abstract class TraceComponent {
    * provided then no-op implementations will be used.
    *
    * @return the {@link TraceConfig} implementation.
+   * @since 0.5
    */
   public abstract TraceConfig getTraceConfig();
 
diff --git a/api/src/main/java/io/opencensus/trace/TraceId.java b/api/src/main/java/io/opencensus/trace/TraceId.java
index 2fad8949..6378bf58 100644
--- a/api/src/main/java/io/opencensus/trace/TraceId.java
+++ b/api/src/main/java/io/opencensus/trace/TraceId.java
@@ -30,13 +30,23 @@ import javax.annotation.concurrent.Immutable;
 /**
  * A class that represents a trace identifier. A valid trace identifier is a 16-byte array with at
  * least one non-zero byte.
+ *
+ * @since 0.5
  */
 @Immutable
 public final class TraceId implements Comparable<TraceId> {
-  /** The size in bytes of the {@code TraceId}. */
+  /**
+   * The size in bytes of the {@code TraceId}.
+   *
+   * @since 0.5
+   */
   public static final int SIZE = 16;
 
-  /** The invalid {@code TraceId}. All bytes are '\0'. */
+  /**
+   * The invalid {@code TraceId}. All bytes are '\0'.
+   *
+   * @since 0.5
+   */
   public static final TraceId INVALID = new TraceId(new byte[SIZE]);
 
   // The internal representation of the TraceId.
@@ -59,6 +69,7 @@ public final class TraceId implements Comparable<TraceId> {
    * @return a {@code TraceId} whose representation is given by the {@code buffer} parameter.
    * @throws NullPointerException if {@code buffer} is null.
    * @throws IllegalArgumentException if {@code buffer.length} is not {@link TraceId#SIZE}.
+   * @since 0.5
    */
   public static TraceId fromBytes(byte[] buffer) {
     checkNotNull(buffer, "buffer");
@@ -78,6 +89,7 @@ public final class TraceId implements Comparable<TraceId> {
    * @throws NullPointerException if {@code src} is null.
    * @throws IndexOutOfBoundsException if {@code srcOffset+TraceId.SIZE} is greater than {@code
    *     src.length}.
+   * @since 0.5
    */
   public static TraceId fromBytes(byte[] src, int srcOffset) {
     byte[] bytes = new byte[SIZE];
@@ -93,6 +105,7 @@ public final class TraceId implements Comparable<TraceId> {
    * @throws NullPointerException if {@code src} is null.
    * @throws IllegalArgumentException if {@code src.length} is not {@code 2 * TraceId.SIZE} OR if
    *     the {@code str} has invalid characters.
+   * @since 0.11
    */
   public static TraceId fromLowerBase16(CharSequence src) {
     checkArgument(
@@ -106,6 +119,7 @@ public final class TraceId implements Comparable<TraceId> {
    *
    * @param random the random number generator.
    * @return a new valid {@code TraceId}.
+   * @since 0.5
    */
   public static TraceId generateRandomId(Random random) {
     byte[] bytes = new byte[SIZE];
@@ -119,6 +133,7 @@ public final class TraceId implements Comparable<TraceId> {
    * Returns the 16-bytes array representation of the {@code TraceId}.
    *
    * @return the 16-bytes array representation of the {@code TraceId}.
+   * @since 0.5
    */
   public byte[] getBytes() {
     return Arrays.copyOf(bytes, SIZE);
@@ -139,6 +154,7 @@ public final class TraceId implements Comparable<TraceId> {
    * @throws NullPointerException if {@code dest} is null.
    * @throws IndexOutOfBoundsException if {@code destOffset+TraceId.SIZE} is greater than {@code
    *     dest.length}.
+   * @since 0.5
    */
   public void copyBytesTo(byte[] dest, int destOffset) {
     System.arraycopy(bytes, 0, dest, destOffset, SIZE);
@@ -149,6 +165,7 @@ public final class TraceId implements Comparable<TraceId> {
    * at least one non-zero byte.
    *
    * @return {@code true} if the {@code TraceId} is valid.
+   * @since 0.5
    */
   public boolean isValid() {
     return !Arrays.equals(bytes, INVALID.bytes);
@@ -158,6 +175,7 @@ public final class TraceId implements Comparable<TraceId> {
    * Returns the lowercase base16 encoding of this {@code TraceId}.
    *
    * @return the lowercase base16 encoding of this {@code TraceId}.
+   * @since 0.11
    */
   public String toLowerBase16() {
     return BaseEncoding.base16().lowerCase().encode(bytes);
diff --git a/api/src/main/java/io/opencensus/trace/TraceOptions.java b/api/src/main/java/io/opencensus/trace/TraceOptions.java
index 2f57f3a7..bd6fe6bd 100644
--- a/api/src/main/java/io/opencensus/trace/TraceOptions.java
+++ b/api/src/main/java/io/opencensus/trace/TraceOptions.java
@@ -30,6 +30,8 @@ import javax.annotation.concurrent.Immutable;
  * A class that represents global trace options. These options are propagated to all child {@link
  * io.opencensus.trace.Span spans}. These determine features such as whether a {@code Span} should
  * be traced. It is implemented as a bitmask.
+ *
+ * @since 0.5
  */
 @Immutable
 public final class TraceOptions {
@@ -38,10 +40,18 @@ public final class TraceOptions {
   // Bit to represent whether trace is sampled or not.
   private static final byte IS_SAMPLED = 0x1;
 
-  /** The size in bytes of the {@code TraceOptions}. */
+  /**
+   * The size in bytes of the {@code TraceOptions}.
+   *
+   * @since 0.5
+   */
   public static final int SIZE = 1;
 
-  /** The default {@code TraceOptions}. */
+  /**
+   * The default {@code TraceOptions}.
+   *
+   * @since 0.5
+   */
   public static final TraceOptions DEFAULT = new TraceOptions(DEFAULT_OPTIONS);
 
   // The set of enabled features is determined by all the enabled bits.
@@ -65,6 +75,7 @@ public final class TraceOptions {
    * @return a {@code TraceOptions} whose representation is given by the {@code buffer} parameter.
    * @throws NullPointerException if {@code buffer} is null.
    * @throws IllegalArgumentException if {@code buffer.length} is not {@link TraceOptions#SIZE}.
+   * @since 0.5
    */
   public static TraceOptions fromBytes(byte[] buffer) {
     checkNotNull(buffer, "buffer");
@@ -83,6 +94,7 @@ public final class TraceOptions {
    * @throws NullPointerException if {@code src} is null.
    * @throws IndexOutOfBoundsException if {@code srcOffset+TraceOptions.SIZE} is greater than {@code
    *     src.length}.
+   * @since 0.5
    */
   public static TraceOptions fromBytes(byte[] src, int srcOffset) {
     checkElementIndex(srcOffset, src.length);
@@ -93,6 +105,7 @@ public final class TraceOptions {
    * Returns the 1-byte array representation of the {@code TraceOptions}.
    *
    * @return the 1-byte array representation of the {@code TraceOptions}.
+   * @since 0.5
    */
   public byte[] getBytes() {
     byte[] bytes = new byte[SIZE];
@@ -115,6 +128,7 @@ public final class TraceOptions {
    * @throws NullPointerException if {@code dest} is null.
    * @throws IndexOutOfBoundsException if {@code destOffset+TraceOptions.SIZE} is greater than
    *     {@code dest.length}.
+   * @since 0.5
    */
   public void copyBytesTo(byte[] dest, int destOffset) {
     checkElementIndex(destOffset, dest.length);
@@ -125,6 +139,7 @@ public final class TraceOptions {
    * Returns a new {@link Builder} with default options.
    *
    * @return a new {@code Builder} with default options.
+   * @since 0.5
    */
   public static Builder builder() {
     return new Builder(DEFAULT_OPTIONS);
@@ -135,6 +150,7 @@ public final class TraceOptions {
    *
    * @param traceOptions the given options set.
    * @return a new {@code Builder} with all given options set.
+   * @since 0.5
    */
   public static Builder builder(TraceOptions traceOptions) {
     return new Builder(traceOptions.options);
@@ -145,6 +161,7 @@ public final class TraceOptions {
    * should be exported to a persistent store.
    *
    * @return a boolean indicating whether the trace is sampled.
+   * @since 0.5
    */
   public boolean isSampled() {
     return hasOption(IS_SAMPLED);
@@ -174,7 +191,11 @@ public final class TraceOptions {
     return MoreObjects.toStringHelper(this).add("sampled", isSampled()).toString();
   }
 
-  /** Builder class for {@link TraceOptions}. */
+  /**
+   * Builder class for {@link TraceOptions}.
+   *
+   * @since 0.5
+   */
   public static final class Builder {
     private byte options;
 
@@ -185,6 +206,7 @@ public final class TraceOptions {
     /**
      * @deprecated Use {@code Builder.setIsSampled(true)}.
      * @return this.
+     * @since 0.5
      */
     @Deprecated
     public Builder setIsSampled() {
@@ -196,6 +218,7 @@ public final class TraceOptions {
      *
      * @param isSampled the sampling bit.
      * @return this.
+     * @since 0.7
      */
     public Builder setIsSampled(boolean isSampled) {
       if (isSampled) {
@@ -211,6 +234,7 @@ public final class TraceOptions {
      * Builds and returns a {@code TraceOptions} with the desired options.
      *
      * @return a {@code TraceOptions} with the desired options.
+     * @since 0.5
      */
     public TraceOptions build() {
       return new TraceOptions(options);
diff --git a/api/src/main/java/io/opencensus/trace/Tracer.java b/api/src/main/java/io/opencensus/trace/Tracer.java
index 22b98da5..f4ac8c65 100644
--- a/api/src/main/java/io/opencensus/trace/Tracer.java
+++ b/api/src/main/java/io/opencensus/trace/Tracer.java
@@ -67,6 +67,8 @@ import javax.annotation.Nullable;
  *   }
  * }
  * }</pre>
+ *
+ * @since 0.5
  */
 public abstract class Tracer {
   private static final NoopTracer noopTracer = new NoopTracer();
@@ -91,6 +93,7 @@ public abstract class Tracer {
    * @return a default {@code Span} that does nothing and has an invalid {@link SpanContext} if no
    *     {@code Span} is associated with the current Context, otherwise the current {@code Span}
    *     from the Context.
+   * @since 0.5
    */
   public final Span getCurrentSpan() {
     Span currentSpan = CurrentSpanUtils.getCurrentSpan();
@@ -145,6 +148,7 @@ public abstract class Tracer {
    * @return an object that defines a scope where the given {@link Span} will be set to the current
    *     Context.
    * @throws NullPointerException if {@code span} is {@code null}.
+   * @since 0.5
    */
   @MustBeClosed
   public final Scope withSpan(Span span) {
@@ -299,6 +303,7 @@ public abstract class Tracer {
    * @param spanName The name of the returned Span.
    * @return a {@code SpanBuilder} to create and start a new {@code Span}.
    * @throws NullPointerException if {@code spanName} is {@code null}.
+   * @since 0.5
    */
   public final SpanBuilder spanBuilder(String spanName) {
     return spanBuilderWithExplicitParent(spanName, CurrentSpanUtils.getCurrentSpan());
@@ -319,6 +324,7 @@ public abstract class Tracer {
    *     build a root {@code Span}.
    * @return a {@code SpanBuilder} to create and start a new {@code Span}.
    * @throws NullPointerException if {@code spanName} is {@code null}.
+   * @since 0.5
    */
   public abstract SpanBuilder spanBuilderWithExplicitParent(String spanName, @Nullable Span parent);
 
@@ -339,6 +345,7 @@ public abstract class Tracer {
    * @param remoteParentSpanContext The remote parent of the returned Span.
    * @return a {@code SpanBuilder} to create and start a new {@code Span}.
    * @throws NullPointerException if {@code spanName} is {@code null}.
+   * @since 0.5
    */
   public abstract SpanBuilder spanBuilderWithRemoteParent(
       String spanName, @Nullable SpanContext remoteParentSpanContext);
diff --git a/api/src/main/java/io/opencensus/trace/Tracing.java b/api/src/main/java/io/opencensus/trace/Tracing.java
index 31d8cdc2..f3673020 100644
--- a/api/src/main/java/io/opencensus/trace/Tracing.java
+++ b/api/src/main/java/io/opencensus/trace/Tracing.java
@@ -26,7 +26,11 @@ import java.util.logging.Level;
 import java.util.logging.Logger;
 import javax.annotation.Nullable;
 
-/** Class that manages a global instance of the {@link TraceComponent}. */
+/**
+ * Class that manages a global instance of the {@link TraceComponent}.
+ *
+ * @since 0.5
+ */
 public final class Tracing {
   private static final Logger logger = Logger.getLogger(Tracing.class.getName());
   private static final TraceComponent traceComponent =
@@ -36,6 +40,7 @@ public final class Tracing {
    * Returns the global {@link Tracer}.
    *
    * @return the global {@code Tracer}.
+   * @since 0.5
    */
   public static Tracer getTracer() {
     return traceComponent.getTracer();
@@ -45,6 +50,7 @@ public final class Tracing {
    * Returns the global {@link PropagationComponent}.
    *
    * @return the global {@code PropagationComponent}.
+   * @since 0.5
    */
   public static PropagationComponent getPropagationComponent() {
     return traceComponent.getPropagationComponent();
@@ -54,6 +60,7 @@ public final class Tracing {
    * Returns the global {@link Clock}.
    *
    * @return the global {@code Clock}.
+   * @since 0.5
    */
   public static Clock getClock() {
     return traceComponent.getClock();
@@ -63,6 +70,7 @@ public final class Tracing {
    * Returns the global {@link ExportComponent}.
    *
    * @return the global {@code ExportComponent}.
+   * @since 0.5
    */
   public static ExportComponent getExportComponent() {
     return traceComponent.getExportComponent();
@@ -72,6 +80,7 @@ public final class Tracing {
    * Returns the global {@link TraceConfig}.
    *
    * @return the global {@code TraceConfig}.
+   * @since 0.5
    */
   public static TraceConfig getTraceConfig() {
     return traceComponent.getTraceConfig();
diff --git a/api/src/main/java/io/opencensus/trace/config/TraceConfig.java b/api/src/main/java/io/opencensus/trace/config/TraceConfig.java
index bebf4a7f..ff701e20 100644
--- a/api/src/main/java/io/opencensus/trace/config/TraceConfig.java
+++ b/api/src/main/java/io/opencensus/trace/config/TraceConfig.java
@@ -19,6 +19,8 @@ package io.opencensus.trace.config;
 /**
  * Global configuration of the trace service. This allows users to change configs for the default
  * sampler, maximum events to be kept, etc. (see {@link TraceParams} for details).
+ *
+ * @since 0.5
  */
 public abstract class TraceConfig {
   private static final NoopTraceConfig NOOP_TRACE_CONFIG = new NoopTraceConfig();
@@ -27,6 +29,7 @@ public abstract class TraceConfig {
    * Returns the active {@code TraceParams}.
    *
    * @return the active {@code TraceParams}.
+   * @since 0.5
    */
   public abstract TraceParams getActiveTraceParams();
 
@@ -34,6 +37,7 @@ public abstract class TraceConfig {
    * Updates the active {@link TraceParams}.
    *
    * @param traceParams the new active {@code TraceParams}.
+   * @since 0.5
    */
   public abstract void updateActiveTraceParams(TraceParams traceParams);
 
@@ -41,6 +45,7 @@ public abstract class TraceConfig {
    * Returns the no-op implementation of the {@code TraceConfig}.
    *
    * @return the no-op implementation of the {@code TraceConfig}.
+   * @since 0.5
    */
   public static TraceConfig getNoopTraceConfig() {
     return NOOP_TRACE_CONFIG;
diff --git a/api/src/main/java/io/opencensus/trace/config/TraceParams.java b/api/src/main/java/io/opencensus/trace/config/TraceParams.java
index c56cc9f7..17dbbb9d 100644
--- a/api/src/main/java/io/opencensus/trace/config/TraceParams.java
+++ b/api/src/main/java/io/opencensus/trace/config/TraceParams.java
@@ -27,7 +27,11 @@ import io.opencensus.trace.Span;
 import io.opencensus.trace.samplers.Samplers;
 import javax.annotation.concurrent.Immutable;
 
-/** Class that holds global trace parameters. */
+/**
+ * Class that holds global trace parameters.
+ *
+ * @since 0.5
+ */
 @AutoValue
 @Immutable
 // Suppress Checker Framework warning about missing @Nullable in generated equals method.
@@ -42,6 +46,11 @@ public abstract class TraceParams {
   private static final int DEFAULT_SPAN_MAX_NUM_NETWORK_EVENTS = 128;
   private static final int DEFAULT_SPAN_MAX_NUM_LINKS = 128;
 
+  /**
+   * Default {@code TraceParams}.
+   *
+   * @since 0.5
+   */
   public static final TraceParams DEFAULT =
       TraceParams.builder()
           .setSampler(DEFAULT_SAMPLER)
@@ -56,6 +65,7 @@ public abstract class TraceParams {
    * io.opencensus.trace.SpanBuilder#setSampler(Sampler)}.
    *
    * @return the global default {@code Sampler}.
+   * @since 0.5
    */
   public abstract Sampler getSampler();
 
@@ -63,6 +73,7 @@ public abstract class TraceParams {
    * Returns the global default max number of attributes per {@link Span}.
    *
    * @return the global default max number of attributes per {@link Span}.
+   * @since 0.5
    */
   public abstract int getMaxNumberOfAttributes();
 
@@ -70,6 +81,7 @@ public abstract class TraceParams {
    * Returns the global default max number of {@link Annotation} events per {@link Span}.
    *
    * @return the global default max number of {@code Annotation} events per {@code Span}.
+   * @since 0.5
    */
   public abstract int getMaxNumberOfAnnotations();
 
@@ -77,6 +89,7 @@ public abstract class TraceParams {
    * Returns the global default max number of {@link NetworkEvent} events per {@link Span}.
    *
    * @return the global default max number of {@code NetworkEvent} events per {@code Span}.
+   * @since 0.5
    */
   public abstract int getMaxNumberOfNetworkEvents();
 
@@ -84,6 +97,7 @@ public abstract class TraceParams {
    * Returns the global default max number of {@link Link} entries per {@link Span}.
    *
    * @return the global default max number of {@code Link} entries per {@code Span}.
+   * @since 0.5
    */
   public abstract int getMaxNumberOfLinks();
 
@@ -95,10 +109,15 @@ public abstract class TraceParams {
    * Returns a {@link Builder} initialized to the same property values as the current instance.
    *
    * @return a {@link Builder} initialized to the same property values as the current instance.
+   * @since 0.5
    */
   public abstract Builder toBuilder();
 
-  /** A {@code Builder} class for {@link TraceParams}. */
+  /**
+   * A {@code Builder} class for {@link TraceParams}.
+   *
+   * @since 0.5
+   */
   @AutoValue.Builder
   public abstract static class Builder {
 
@@ -108,6 +127,7 @@ public abstract class TraceParams {
      *
      * @param sampler the global default {@code Sampler}.
      * @return this.
+     * @since 0.5
      */
     public abstract Builder setSampler(Sampler sampler);
 
@@ -117,6 +137,7 @@ public abstract class TraceParams {
      * @param maxNumberOfAttributes the global default max number of attributes per {@link Span}. It
      *     must be positive otherwise {@link #build()} will throw an exception.
      * @return this.
+     * @since 0.5
      */
     public abstract Builder setMaxNumberOfAttributes(int maxNumberOfAttributes);
 
@@ -126,6 +147,7 @@ public abstract class TraceParams {
      * @param maxNumberOfAnnotations the global default max number of {@link Annotation} events per
      *     {@link Span}. It must be positive otherwise {@link #build()} will throw an exception.
      * @return this.
+     * @since 0.5
      */
     public abstract Builder setMaxNumberOfAnnotations(int maxNumberOfAnnotations);
 
@@ -135,6 +157,7 @@ public abstract class TraceParams {
      * @param maxNumberOfNetworkEvents the global default max number of {@link NetworkEvent} events
      *     per {@link Span}. It must be positive otherwise {@link #build()} will throw an exception.
      * @return this.
+     * @since 0.5
      */
     public abstract Builder setMaxNumberOfNetworkEvents(int maxNumberOfNetworkEvents);
 
@@ -144,6 +167,7 @@ public abstract class TraceParams {
      * @param maxNumberOfLinks the global default max number of {@link Link} entries per {@link
      *     Span}. It must be positive otherwise {@link #build()} will throw an exception.
      * @return this.
+     * @since 0.5
      */
     public abstract Builder setMaxNumberOfLinks(int maxNumberOfLinks);
 
@@ -155,6 +179,7 @@ public abstract class TraceParams {
      * @return a {@code TraceParams} with the desired values.
      * @throws NullPointerException if the sampler is {@code null}.
      * @throws IllegalArgumentException if any of the max numbers are not positive.
+     * @since 0.5
      */
     public TraceParams build() {
       TraceParams traceParams = autoBuild();
diff --git a/api/src/main/java/io/opencensus/trace/export/ExportComponent.java b/api/src/main/java/io/opencensus/trace/export/ExportComponent.java
index 7e2eb88e..63447a76 100644
--- a/api/src/main/java/io/opencensus/trace/export/ExportComponent.java
+++ b/api/src/main/java/io/opencensus/trace/export/ExportComponent.java
@@ -23,6 +23,8 @@ import io.opencensus.trace.TraceOptions;
  * and {@link SampledSpanStore}.
  *
  * <p>Unless otherwise noted all methods (on component) results are cacheable.
+ *
+ * @since 0.5
  */
 public abstract class ExportComponent {
 
@@ -30,6 +32,7 @@ public abstract class ExportComponent {
    * Returns the no-op implementation of the {@code ExportComponent}.
    *
    * @return the no-op implementation of the {@code ExportComponent}.
+   * @since 0.5
    */
   public static ExportComponent newNoopExportComponent() {
     return new NoopExportComponent();
@@ -41,6 +44,7 @@ public abstract class ExportComponent {
    *
    * @return the implementation of the {@code SpanExporter} or no-op if no implementation linked in
    *     the binary.
+   * @since 0.5
    */
   public abstract SpanExporter getSpanExporter();
 
@@ -49,6 +53,7 @@ public abstract class ExportComponent {
    * all the current active spans.
    *
    * @return the {@code RunningSpanStore}.
+   * @since 0.5
    */
   public abstract RunningSpanStore getRunningSpanStore();
 
@@ -57,6 +62,7 @@ public abstract class ExportComponent {
    * as latency based sampled spans, error based sampled spans.
    *
    * @return the {@code SampledSpanStore}.
+   * @since 0.5
    */
   public abstract SampledSpanStore getSampledSpanStore();
 
diff --git a/api/src/main/java/io/opencensus/trace/export/RunningSpanStore.java b/api/src/main/java/io/opencensus/trace/export/RunningSpanStore.java
index 209afe05..fbfc5ff1 100644
--- a/api/src/main/java/io/opencensus/trace/export/RunningSpanStore.java
+++ b/api/src/main/java/io/opencensus/trace/export/RunningSpanStore.java
@@ -33,6 +33,8 @@ import javax.annotation.concurrent.ThreadSafe;
  * <p>The running spans tracking is available for all the spans with the option {@link
  * io.opencensus.trace.Span.Options#RECORD_EVENTS}. This functionality allows users to debug stuck
  * operations or long living operations.
+ *
+ * @since 0.5
  */
 @ThreadSafe
 public abstract class RunningSpanStore {
@@ -54,6 +56,7 @@ public abstract class RunningSpanStore {
    * Returns the summary of all available data such, as number of running spans.
    *
    * @return the summary of all available data.
+   * @since 0.5
    */
   public abstract Summary getSummary();
 
@@ -62,10 +65,15 @@ public abstract class RunningSpanStore {
    *
    * @param filter used to filter the returned spans.
    * @return a list of running spans that match the {@code Filter}.
+   * @since 0.5
    */
   public abstract Collection<SpanData> getRunningSpans(Filter filter);
 
-  /** The summary of all available data. */
+  /**
+   * The summary of all available data.
+   *
+   * @since 0.5
+   */
   @AutoValue
   @Immutable
   // Suppress Checker Framework warning about missing @Nullable in generated equals method.
@@ -81,6 +89,7 @@ public abstract class RunningSpanStore {
      * @param perSpanNameSummary a map with summary for each span name.
      * @return a new instance of {@code Summary}.
      * @throws NullPointerException if {@code perSpanNameSummary} is {@code null}.
+     * @since 0.5
      */
     public static Summary create(Map<String, PerSpanNameSummary> perSpanNameSummary) {
       return new AutoValue_RunningSpanStore_Summary(
@@ -93,11 +102,16 @@ public abstract class RunningSpanStore {
      * Returns a map with summary of available data for each span name.
      *
      * @return a map with all the span names and the summary.
+     * @since 0.5
      */
     public abstract Map<String, PerSpanNameSummary> getPerSpanNameSummary();
   }
 
-  /** Summary of all available data for a span name. */
+  /**
+   * Summary of all available data for a span name.
+   *
+   * @since 0.5
+   */
   @AutoValue
   @Immutable
   // Suppress Checker Framework warning about missing @Nullable in generated equals method.
@@ -113,6 +127,7 @@ public abstract class RunningSpanStore {
      * @param numRunningSpans the number of running spans.
      * @return a new instance of {@code PerSpanNameSummary}.
      * @throws IllegalArgumentException if {@code numRunningSpans} is negative.
+     * @since 0.5
      */
     public static PerSpanNameSummary create(int numRunningSpans) {
       checkArgument(numRunningSpans >= 0, "Negative numRunningSpans.");
@@ -123,6 +138,7 @@ public abstract class RunningSpanStore {
      * Returns the number of running spans.
      *
      * @return the number of running spans.
+     * @since 0.5
      */
     public abstract int getNumRunningSpans();
   }
@@ -130,6 +146,8 @@ public abstract class RunningSpanStore {
   /**
    * Filter for running spans. Used to filter results returned by the {@link
    * #getRunningSpans(Filter)} request.
+   *
+   * @since 0.5
    */
   @AutoValue
   @Immutable
@@ -151,6 +169,7 @@ public abstract class RunningSpanStore {
      * @return a new instance of {@code Filter}.
      * @throws NullPointerException if {@code spanName} is {@code null}.
      * @throws IllegalArgumentException if {@code maxSpansToReturn} is negative.
+     * @since 0.5
      */
     public static Filter create(String spanName, int maxSpansToReturn) {
       checkArgument(maxSpansToReturn >= 0, "Negative maxSpansToReturn.");
@@ -161,6 +180,7 @@ public abstract class RunningSpanStore {
      * Returns the span name.
      *
      * @return the span name.
+     * @since 0.5
      */
     public abstract String getSpanName();
 
@@ -168,6 +188,7 @@ public abstract class RunningSpanStore {
      * Returns the maximum number of spans to be returned. {@code 0} means all.
      *
      * @return the maximum number of spans to be returned.
+     * @since 0.5
      */
     public abstract int getMaxSpansToReturn();
   }
diff --git a/api/src/main/java/io/opencensus/trace/export/SampledSpanStore.java b/api/src/main/java/io/opencensus/trace/export/SampledSpanStore.java
index c04b19f6..67a40567 100644
--- a/api/src/main/java/io/opencensus/trace/export/SampledSpanStore.java
+++ b/api/src/main/java/io/opencensus/trace/export/SampledSpanStore.java
@@ -45,6 +45,8 @@ import javax.annotation.concurrent.ThreadSafe;
  * store samples based on latency for succeeded operations or based on error code for failed
  * operations. To activate this, users MUST manually configure all the span names for which samples
  * will be collected (see {@link #registerSpanNamesForCollection(Collection)}).
+ *
+ * @since 0.5
  */
 @ThreadSafe
 public abstract class SampledSpanStore {
@@ -70,6 +72,7 @@ public abstract class SampledSpanStore {
    * #registerSpanNamesForCollection(Collection)}.
    *
    * @return the summary of all available data.
+   * @since 0.5
    */
   public abstract Summary getSummary();
 
@@ -82,6 +85,7 @@ public abstract class SampledSpanStore {
    *
    * @param filter used to filter the returned sampled spans.
    * @return a list of succeeded spans that match the {@code filter}.
+   * @since 0.5
    */
   public abstract Collection<SpanData> getLatencySampledSpans(LatencyFilter filter);
 
@@ -94,6 +98,7 @@ public abstract class SampledSpanStore {
    *
    * @param filter used to filter the returned sampled spans.
    * @return a list of failed spans that match the {@code filter}.
+   * @since 0.5
    */
   public abstract Collection<SpanData> getErrorSampledSpans(ErrorFilter filter);
 
@@ -104,6 +109,7 @@ public abstract class SampledSpanStore {
    * <p>If called multiple times the library keeps the list of unique span names from all the calls.
    *
    * @param spanNames list of span names for which the library will collect samples.
+   * @since 0.5
    */
   public abstract void registerSpanNamesForCollection(Collection<String> spanNames);
 
@@ -115,6 +121,7 @@ public abstract class SampledSpanStore {
    * This method allows users to remove span names from that list.
    *
    * @param spanNames list of span names for which the library will no longer collect samples.
+   * @since 0.5
    */
   public abstract void unregisterSpanNamesForCollection(Collection<String> spanNames);
 
@@ -123,11 +130,16 @@ public abstract class SampledSpanStore {
    * library will collect latency based sampled spans and error based sampled spans.
    *
    * @return the set of unique span names registered to the library.
+   * @since 0.7
    */
   @VisibleForTesting
   public abstract Set<String> getRegisteredSpanNamesForCollection();
 
-  /** The summary of all available data. */
+  /**
+   * The summary of all available data.
+   *
+   * @since 0.5
+   */
   @AutoValue
   @Immutable
   // Suppress Checker Framework warning about missing @Nullable in generated equals method.
@@ -143,6 +155,7 @@ public abstract class SampledSpanStore {
      * @param perSpanNameSummary a map with summary for each span name.
      * @return a new instance of {@code Summary}.
      * @throws NullPointerException if {@code perSpanNameSummary} is {@code null}.
+     * @since 0.5
      */
     public static Summary create(Map<String, PerSpanNameSummary> perSpanNameSummary) {
       return new AutoValue_SampledSpanStore_Summary(
@@ -155,11 +168,16 @@ public abstract class SampledSpanStore {
      * Returns a map with summary of available data for each span name.
      *
      * @return a map with all the span names and the summary.
+     * @since 0.5
      */
     public abstract Map<String, PerSpanNameSummary> getPerSpanNameSummary();
   }
 
-  /** Summary of all available data for a span name. */
+  /**
+   * Summary of all available data for a span name.
+   *
+   * @since 0.5
+   */
   @AutoValue
   @Immutable
   // Suppress Checker Framework warning about missing @Nullable in generated equals method.
@@ -177,6 +195,7 @@ public abstract class SampledSpanStore {
      * @return a new instance of {@code PerSpanNameSummary}.
      * @throws NullPointerException if {@code numbersOfLatencySampledSpans} or {@code
      *     numbersOfErrorSampledSpans} are {@code null}.
+     * @since 0.5
      */
     public static PerSpanNameSummary create(
         Map<LatencyBucketBoundaries, Integer> numbersOfLatencySampledSpans,
@@ -197,6 +216,7 @@ public abstract class SampledSpanStore {
      * #registerSpanNamesForCollection(Collection)}.
      *
      * @return the number of sampled spans in all the latency buckets.
+     * @since 0.5
      */
     public abstract Map<LatencyBucketBoundaries, Integer> getNumbersOfLatencySampledSpans();
 
@@ -207,6 +227,7 @@ public abstract class SampledSpanStore {
      * #registerSpanNamesForCollection(Collection)}.
      *
      * @return the number of sampled spans in all the error buckets.
+     * @since 0.5
      */
     public abstract Map<CanonicalCode, Integer> getNumbersOfErrorSampledSpans();
   }
@@ -215,25 +236,71 @@ public abstract class SampledSpanStore {
    * The latency buckets boundaries. Samples based on latency for successful spans (the status of
    * the span has a canonical code equal to {@link CanonicalCode#OK}) are collected in one of these
    * latency buckets.
+   *
+   * @since 0.5
    */
   public enum LatencyBucketBoundaries {
-    // Stores finished successful requests of duration within the interval [0, 10us)
+    /**
+     * Stores finished successful requests of duration within the interval [0, 10us)
+     *
+     * @since 0.5
+     */
     ZERO_MICROSx10(0, TimeUnit.MICROSECONDS.toNanos(10)),
-    // Stores finished successful requests of duration within the interval [10us, 100us)
+
+    /**
+     * Stores finished successful requests of duration within the interval [10us, 100us)
+     *
+     * @since 0.5
+     */
     MICROSx10_MICROSx100(TimeUnit.MICROSECONDS.toNanos(10), TimeUnit.MICROSECONDS.toNanos(100)),
-    // Stores finished successful requests of duration within the interval [100us, 1ms)
+
+    /**
+     * Stores finished successful requests of duration within the interval [100us, 1ms)
+     *
+     * @since 0.5
+     */
     MICROSx100_MILLIx1(TimeUnit.MICROSECONDS.toNanos(100), TimeUnit.MILLISECONDS.toNanos(1)),
-    // Stores finished successful requests of duration within the interval [1ms, 10ms)
+
+    /**
+     * Stores finished successful requests of duration within the interval [1ms, 10ms)
+     *
+     * @since 0.5
+     */
     MILLIx1_MILLIx10(TimeUnit.MILLISECONDS.toNanos(1), TimeUnit.MILLISECONDS.toNanos(10)),
-    // Stores finished successful requests of duration within the interval [10ms, 100ms)
+
+    /**
+     * Stores finished successful requests of duration within the interval [10ms, 100ms)
+     *
+     * @since 0.5
+     */
     MILLIx10_MILLIx100(TimeUnit.MILLISECONDS.toNanos(10), TimeUnit.MILLISECONDS.toNanos(100)),
-    // Stores finished successful requests of duration within the interval [100ms, 1sec)
+
+    /**
+     * Stores finished successful requests of duration within the interval [100ms, 1sec)
+     *
+     * @since 0.5
+     */
     MILLIx100_SECONDx1(TimeUnit.MILLISECONDS.toNanos(100), TimeUnit.SECONDS.toNanos(1)),
-    // Stores finished successful requests of duration within the interval [1sec, 10sec)
+
+    /**
+     * Stores finished successful requests of duration within the interval [1sec, 10sec)
+     *
+     * @since 0.5
+     */
     SECONDx1_SECONDx10(TimeUnit.SECONDS.toNanos(1), TimeUnit.SECONDS.toNanos(10)),
-    // Stores finished successful requests of duration within the interval [10sec, 100sec)
+
+    /**
+     * Stores finished successful requests of duration within the interval [10sec, 100sec)
+     *
+     * @since 0.5
+     */
     SECONDx10_SECONDx100(TimeUnit.SECONDS.toNanos(10), TimeUnit.SECONDS.toNanos(100)),
-    // Stores finished successful requests of duration >= 100sec
+
+    /**
+     * Stores finished successful requests of duration &gt;= 100sec
+     *
+     * @since 0.5
+     */
     SECONDx100_MAX(TimeUnit.SECONDS.toNanos(100), Long.MAX_VALUE);
 
     /**
@@ -251,6 +318,7 @@ public abstract class SampledSpanStore {
      * Returns the latency lower bound of the bucket.
      *
      * @return the latency lower bound of the bucket.
+     * @since 0.5
      */
     public long getLatencyLowerNs() {
       return latencyLowerNs;
@@ -260,6 +328,7 @@ public abstract class SampledSpanStore {
      * Returns the latency upper bound of the bucket.
      *
      * @return the latency upper bound of the bucket.
+     * @since 0.5
      */
     public long getLatencyUpperNs() {
       return latencyUpperNs;
@@ -272,6 +341,8 @@ public abstract class SampledSpanStore {
   /**
    * Filter for latency based sampled spans. Used to filter results returned by the {@link
    * #getLatencySampledSpans(LatencyFilter)} request.
+   *
+   * @since 0.5
    */
   @AutoValue
   @Immutable
@@ -296,6 +367,7 @@ public abstract class SampledSpanStore {
      * @throws NullPointerException if {@code spanName} is {@code null}.
      * @throws IllegalArgumentException if {@code maxSpansToReturn} or {@code latencyLowerNs} or
      *     {@code latencyUpperNs} are negative.
+     * @since 0.5
      */
     public static LatencyFilter create(
         String spanName, long latencyLowerNs, long latencyUpperNs, int maxSpansToReturn) {
@@ -310,6 +382,7 @@ public abstract class SampledSpanStore {
      * Returns the span name used by this filter.
      *
      * @return the span name used by this filter.
+     * @since 0.5
      */
     public abstract String getSpanName();
 
@@ -317,6 +390,7 @@ public abstract class SampledSpanStore {
      * Returns the latency lower bound of this bucket (inclusive).
      *
      * @return the latency lower bound of this bucket.
+     * @since 0.5
      */
     public abstract long getLatencyLowerNs();
 
@@ -324,6 +398,7 @@ public abstract class SampledSpanStore {
      * Returns the latency upper bound of this bucket (exclusive).
      *
      * @return the latency upper bound of this bucket.
+     * @since 0.5
      */
     public abstract long getLatencyUpperNs();
 
@@ -331,6 +406,7 @@ public abstract class SampledSpanStore {
      * Returns the maximum number of spans to be returned. {@code 0} means all.
      *
      * @return the maximum number of spans to be returned.
+     * @since 0.5
      */
     public abstract int getMaxSpansToReturn();
   }
@@ -338,6 +414,8 @@ public abstract class SampledSpanStore {
   /**
    * Filter for error based sampled spans. Used to filter results returned by the {@link
    * #getErrorSampledSpans(ErrorFilter)} request.
+   *
+   * @since 0.5
    */
   @AutoValue
   @Immutable
@@ -362,6 +440,7 @@ public abstract class SampledSpanStore {
      * @throws NullPointerException if {@code spanName} is {@code null}.
      * @throws IllegalArgumentException if {@code canonicalCode} is {@link CanonicalCode#OK} or
      *     {@code maxSpansToReturn} is negative.
+     * @since 0.5
      */
     public static ErrorFilter create(
         String spanName, @Nullable CanonicalCode canonicalCode, int maxSpansToReturn) {
@@ -376,6 +455,7 @@ public abstract class SampledSpanStore {
      * Returns the span name used by this filter.
      *
      * @return the span name used by this filter.
+     * @since 0.5
      */
     public abstract String getSpanName();
 
@@ -384,6 +464,7 @@ public abstract class SampledSpanStore {
      * CanonicalCode#OK}. If {@code null} then all errors match.
      *
      * @return the canonical code used by this filter.
+     * @since 0.5
      */
     @Nullable
     public abstract CanonicalCode getCanonicalCode();
@@ -393,6 +474,7 @@ public abstract class SampledSpanStore {
      * {@code SpanData}. {@code 0} means all.
      *
      * @return the maximum number of spans to be returned.
+     * @since 0.5
      */
     public abstract int getMaxSpansToReturn();
   }
diff --git a/api/src/main/java/io/opencensus/trace/export/SpanData.java b/api/src/main/java/io/opencensus/trace/export/SpanData.java
index 498c142e..546b65b6 100644
--- a/api/src/main/java/io/opencensus/trace/export/SpanData.java
+++ b/api/src/main/java/io/opencensus/trace/export/SpanData.java
@@ -40,7 +40,11 @@ import javax.annotation.concurrent.Immutable;
 import org.checkerframework.dataflow.qual.Deterministic;
 */
 
-/** Immutable representation of all data collected by the {@link Span} class. */
+/**
+ * Immutable representation of all data collected by the {@link Span} class.
+ *
+ * @since 0.5
+ */
 @Immutable
 @AutoValue
 // Suppress Checker Framework warning about missing @Nullable in generated equals method.
@@ -68,6 +72,7 @@ public abstract class SpanData {
    * @param endTimestamp the end {@code Timestamp} of the {@code Span}. {@code null} if the {@code
    *     Span} is still active.
    * @return a new immutable {@code SpanData}.
+   * @since 0.5
    */
   public static SpanData create(
       SpanContext context,
@@ -101,6 +106,7 @@ public abstract class SpanData {
    * Returns the {@code SpanContext} associated with this {@code Span}.
    *
    * @return the {@code SpanContext} associated with this {@code Span}.
+   * @since 0.5
    */
   public abstract SpanContext getContext();
 
@@ -108,6 +114,7 @@ public abstract class SpanData {
    * Returns the parent {@code SpanId} or {@code null} if the {@code Span} is a root {@code Span}.
    *
    * @return the parent {@code SpanId} or {@code null} if the {@code Span} is a root {@code Span}.
+   * @since 0.5
    */
   @Nullable
   /*@Deterministic*/
@@ -119,6 +126,7 @@ public abstract class SpanData {
    *
    * @return {@code true} if the parent is on a different process. {@code null} if this is a root
    *     span.
+   * @since 0.5
    */
   @Nullable
   public abstract Boolean getHasRemoteParent();
@@ -127,6 +135,7 @@ public abstract class SpanData {
    * Returns the name of this {@code Span}.
    *
    * @return the name of this {@code Span}.
+   * @since 0.5
    */
   public abstract String getName();
 
@@ -134,6 +143,7 @@ public abstract class SpanData {
    * Returns the start {@code Timestamp} of this {@code Span}.
    *
    * @return the start {@code Timestamp} of this {@code Span}.
+   * @since 0.5
    */
   public abstract Timestamp getStartTimestamp();
 
@@ -141,6 +151,7 @@ public abstract class SpanData {
    * Returns the attributes recorded for this {@code Span}.
    *
    * @return the attributes recorded for this {@code Span}.
+   * @since 0.5
    */
   public abstract Attributes getAttributes();
 
@@ -148,6 +159,7 @@ public abstract class SpanData {
    * Returns the annotations recorded for this {@code Span}.
    *
    * @return the annotations recorded for this {@code Span}.
+   * @since 0.5
    */
   public abstract TimedEvents<Annotation> getAnnotations();
 
@@ -155,6 +167,7 @@ public abstract class SpanData {
    * Returns network events recorded for this {@code Span}.
    *
    * @return network events recorded for this {@code Span}.
+   * @since 0.5
    */
   public abstract TimedEvents<NetworkEvent> getNetworkEvents();
 
@@ -162,6 +175,7 @@ public abstract class SpanData {
    * Returns links recorded for this {@code Span}.
    *
    * @return links recorded for this {@code Span}.
+   * @since 0.5
    */
   public abstract Links getLinks();
 
@@ -172,6 +186,7 @@ public abstract class SpanData {
    * <p>This information is not always available.
    *
    * @return the number of child spans that were generated while the {@code Span} was running.
+   * @since 0.5
    */
   @Nullable
   public abstract Integer getChildSpanCount();
@@ -180,6 +195,7 @@ public abstract class SpanData {
    * Returns the {@code Status} or {@code null} if {@code Span} is still active.
    *
    * @return the {@code Status} or {@code null} if {@code Span} is still active.
+   * @since 0.5
    */
   @Nullable
   /*@Deterministic*/
@@ -189,6 +205,7 @@ public abstract class SpanData {
    * Returns the end {@code Timestamp} or {@code null} if the {@code Span} is still active.
    *
    * @return the end {@code Timestamp} or {@code null} if the {@code Span} is still active.
+   * @since 0.5
    */
   @Nullable
   /*@Deterministic*/
@@ -200,6 +217,7 @@ public abstract class SpanData {
    * A timed event representation.
    *
    * @param <T> the type of value that is timed.
+   * @since 0.5
    */
   @Immutable
   @AutoValue
@@ -214,6 +232,7 @@ public abstract class SpanData {
      * @param event the event.
      * @param <T> the type of value that is timed.
      * @return a new immutable {@code TimedEvent<T>}
+     * @since 0.5
      */
     public static <T> TimedEvent<T> create(Timestamp timestamp, T event) {
       return new AutoValue_SpanData_TimedEvent<T>(timestamp, event);
@@ -223,6 +242,7 @@ public abstract class SpanData {
      * Returns the {@code Timestamp} of this event.
      *
      * @return the {@code Timestamp} of this event.
+     * @since 0.5
      */
     public abstract Timestamp getTimestamp();
 
@@ -230,6 +250,7 @@ public abstract class SpanData {
      * Returns the event.
      *
      * @return the event.
+     * @since 0.5
      */
     /*@Deterministic*/
     public abstract T getEvent();
@@ -241,6 +262,7 @@ public abstract class SpanData {
    * A list of timed events and the number of dropped events representation.
    *
    * @param <T> the type of value that is timed.
+   * @since 0.5
    */
   @Immutable
   @AutoValue
@@ -255,6 +277,7 @@ public abstract class SpanData {
      * @param droppedEventsCount the number of dropped events.
      * @param <T> the type of value that is timed.
      * @return a new immutable {@code TimedEvents<T>}
+     * @since 0.5
      */
     public static <T> TimedEvents<T> create(List<TimedEvent<T>> events, int droppedEventsCount) {
       return new AutoValue_SpanData_TimedEvents<T>(
@@ -267,6 +290,7 @@ public abstract class SpanData {
      * Returns the list of events.
      *
      * @return the list of events.
+     * @since 0.5
      */
     public abstract List<TimedEvent<T>> getEvents();
 
@@ -274,13 +298,18 @@ public abstract class SpanData {
      * Returns the number of dropped events.
      *
      * @return the number of dropped events.
+     * @since 0.5
      */
     public abstract int getDroppedEventsCount();
 
     TimedEvents() {}
   }
 
-  /** A set of attributes and the number of dropped attributes representation. */
+  /**
+   * A set of attributes and the number of dropped attributes representation.
+   *
+   * @since 0.5
+   */
   @Immutable
   @AutoValue
   // Suppress Checker Framework warning about missing @Nullable in generated equals method.
@@ -293,6 +322,7 @@ public abstract class SpanData {
      * @param attributeMap the set of attributes.
      * @param droppedAttributesCount the number of dropped attributes.
      * @return a new immutable {@code Attributes}.
+     * @since 0.5
      */
     public static Attributes create(
         Map<String, AttributeValue> attributeMap, int droppedAttributesCount) {
@@ -308,6 +338,7 @@ public abstract class SpanData {
      * Returns the set of attributes.
      *
      * @return the set of attributes.
+     * @since 0.5
      */
     public abstract Map<String, AttributeValue> getAttributeMap();
 
@@ -315,13 +346,18 @@ public abstract class SpanData {
      * Returns the number of dropped attributes.
      *
      * @return the number of dropped attributes.
+     * @since 0.5
      */
     public abstract int getDroppedAttributesCount();
 
     Attributes() {}
   }
 
-  /** A list of links and the number of dropped links representation. */
+  /**
+   * A list of links and the number of dropped links representation.
+   *
+   * @since 0.5
+   */
   @Immutable
   @AutoValue
   // Suppress Checker Framework warning about missing @Nullable in generated equals method.
@@ -334,6 +370,7 @@ public abstract class SpanData {
      * @param links the list of links.
      * @param droppedLinksCount the number of dropped links.
      * @return a new immutable {@code Links}.
+     * @since 0.5
      */
     public static Links create(List<Link> links, int droppedLinksCount) {
       return new AutoValue_SpanData_Links(
@@ -345,6 +382,7 @@ public abstract class SpanData {
      * Returns the list of links.
      *
      * @return the list of links.
+     * @since 0.5
      */
     public abstract List<Link> getLinks();
 
@@ -352,6 +390,7 @@ public abstract class SpanData {
      * Returns the number of dropped links.
      *
      * @return the number of dropped links.
+     * @since 0.5
      */
     public abstract int getDroppedLinksCount();
 
diff --git a/api/src/main/java/io/opencensus/trace/export/SpanExporter.java b/api/src/main/java/io/opencensus/trace/export/SpanExporter.java
index e872904f..73ac5265 100644
--- a/api/src/main/java/io/opencensus/trace/export/SpanExporter.java
+++ b/api/src/main/java/io/opencensus/trace/export/SpanExporter.java
@@ -24,6 +24,8 @@ import javax.annotation.concurrent.ThreadSafe;
 /**
  * A service that is used by the library to export {@code SpanData} for all the spans that are part
  * of a distributed sampled trace (see {@link TraceOptions#isSampled()}).
+ *
+ * @since 0.5
  */
 @ThreadSafe
 public abstract class SpanExporter {
@@ -33,6 +35,7 @@ public abstract class SpanExporter {
    * Returns the no-op implementation of the {@code ExportComponent}.
    *
    * @return the no-op implementation of the {@code ExportComponent}.
+   * @since 0.5
    */
   public static SpanExporter getNoopSpanExporter() {
     return NOOP_SPAN_EXPORTER;
@@ -44,6 +47,7 @@ public abstract class SpanExporter {
    *
    * @param name the name of the service handler. Must be unique for each service.
    * @param handler the service handler that is called for each ended sampled span.
+   * @since 0.5
    */
   public abstract void registerHandler(String name, Handler handler);
 
@@ -51,6 +55,7 @@ public abstract class SpanExporter {
    * Unregisters the service handler with the provided name.
    *
    * @param name the name of the service handler that will be unregistered.
+   * @since 0.5
    */
   public abstract void unregisterHandler(String name);
 
@@ -60,6 +65,8 @@ public abstract class SpanExporter {
    *
    * <p>To export data this MUST be register to to the ExportComponent using {@link
    * #registerHandler(String, Handler)}.
+   *
+   * @since 0.5
    */
   public abstract static class Handler {
 
@@ -73,6 +80,7 @@ public abstract class SpanExporter {
      * different thread if possible.
      *
      * @param spanDataList a list of {@code SpanData} objects to be exported.
+     * @since 0.5
      */
     public abstract void export(Collection<SpanData> spanDataList);
   }
diff --git a/api/src/main/java/io/opencensus/trace/propagation/BinaryFormat.java b/api/src/main/java/io/opencensus/trace/propagation/BinaryFormat.java
index f9c59142..e07afd12 100644
--- a/api/src/main/java/io/opencensus/trace/propagation/BinaryFormat.java
+++ b/api/src/main/java/io/opencensus/trace/propagation/BinaryFormat.java
@@ -60,6 +60,8 @@ import java.text.ParseException;
  *   }
  * }
  * }</pre>
+ *
+ * @since 0.5
  */
 public abstract class BinaryFormat {
   static final NoopBinaryFormat NOOP_BINARY_FORMAT = new NoopBinaryFormat();
@@ -69,6 +71,7 @@ public abstract class BinaryFormat {
    * @param spanContext the {@code SpanContext} to serialize.
    * @return the serialized binary value.
    * @throws NullPointerException if the {@code spanContext} is {@code null}.
+   * @since 0.5
    */
   @Deprecated
   public byte[] toBinaryValue(SpanContext spanContext) {
@@ -81,6 +84,7 @@ public abstract class BinaryFormat {
    * @param spanContext the {@code SpanContext} to serialize.
    * @return the serialized binary value.
    * @throws NullPointerException if the {@code spanContext} is {@code null}.
+   * @since 0.7
    */
   public byte[] toByteArray(SpanContext spanContext) {
     // Implementation must override this method.
@@ -93,6 +97,7 @@ public abstract class BinaryFormat {
    * @return the parsed {@code SpanContext}.
    * @throws NullPointerException if the {@code input} is {@code null}.
    * @throws ParseException if the version is not supported or the input is invalid
+   * @since 0.5
    */
   @Deprecated
   public SpanContext fromBinaryValue(byte[] bytes) throws ParseException {
@@ -110,6 +115,7 @@ public abstract class BinaryFormat {
    * @return the parsed {@code SpanContext}.
    * @throws NullPointerException if the {@code input} is {@code null}.
    * @throws SpanContextParseException if the version is not supported or the input is invalid
+   * @since 0.7
    */
   public SpanContext fromByteArray(byte[] bytes) throws SpanContextParseException {
     // Implementation must override this method.
diff --git a/api/src/main/java/io/opencensus/trace/propagation/PropagationComponent.java b/api/src/main/java/io/opencensus/trace/propagation/PropagationComponent.java
index a56c6d13..a90f0419 100644
--- a/api/src/main/java/io/opencensus/trace/propagation/PropagationComponent.java
+++ b/api/src/main/java/io/opencensus/trace/propagation/PropagationComponent.java
@@ -22,6 +22,8 @@ import io.opencensus.common.ExperimentalApi;
  * Container class for all the supported propagation formats. Currently supports only Binary format
  * (see {@link BinaryFormat}) and B3 Text format (see {@link TextFormat}) but more formats will be
  * added.
+ *
+ * @since 0.5
  */
 public abstract class PropagationComponent {
   private static final PropagationComponent NOOP_PROPAGATION_COMPONENT =
@@ -32,6 +34,7 @@ public abstract class PropagationComponent {
    * provided then no-op implementation will be used.
    *
    * @return the {@code BinaryFormat} implementation.
+   * @since 0.5
    */
   public abstract BinaryFormat getBinaryFormat();
 
@@ -50,6 +53,7 @@ public abstract class PropagationComponent {
    * Returns an instance that contains no-op implementations for all the instances.
    *
    * @return an instance that contains no-op implementations for all the instances.
+   * @since 0.5
    */
   public static PropagationComponent getNoopPropagationComponent() {
     return NOOP_PROPAGATION_COMPONENT;
diff --git a/api/src/main/java/io/opencensus/trace/propagation/SpanContextParseException.java b/api/src/main/java/io/opencensus/trace/propagation/SpanContextParseException.java
index fa7f2d4e..80d42af5 100644
--- a/api/src/main/java/io/opencensus/trace/propagation/SpanContextParseException.java
+++ b/api/src/main/java/io/opencensus/trace/propagation/SpanContextParseException.java
@@ -16,7 +16,11 @@
 
 package io.opencensus.trace.propagation;
 
-/** Exception thrown when a {@link io.opencensus.trace.SpanContext} cannot be parsed. */
+/**
+ * Exception thrown when a {@link io.opencensus.trace.SpanContext} cannot be parsed.
+ *
+ * @since 0.7
+ */
 public final class SpanContextParseException extends Exception {
   private static final long serialVersionUID = 0L;
 
@@ -24,6 +28,7 @@ public final class SpanContextParseException extends Exception {
    * Constructs a new {@code SpanContextParseException} with the given message.
    *
    * @param message a message describing the parse error.
+   * @since 0.7
    */
   public SpanContextParseException(String message) {
     super(message);
@@ -34,6 +39,7 @@ public final class SpanContextParseException extends Exception {
    *
    * @param message a message describing the parse error.
    * @param cause the cause of the parse error.
+   * @since 0.7
    */
   public SpanContextParseException(String message, Throwable cause) {
     super(message, cause);
diff --git a/api/src/main/java/io/opencensus/trace/propagation/TextFormat.java b/api/src/main/java/io/opencensus/trace/propagation/TextFormat.java
index 25880917..eaa7bf00 100644
--- a/api/src/main/java/io/opencensus/trace/propagation/TextFormat.java
+++ b/api/src/main/java/io/opencensus/trace/propagation/TextFormat.java
@@ -73,6 +73,8 @@ import javax.annotation.Nullable;
  *   span.end()
  * }
  * }</pre>
+ *
+ * @since 0.11
  */
 @ExperimentalApi
 public abstract class TextFormat {
@@ -85,6 +87,8 @@ public abstract class TextFormat {
    * <p>For example, if the carrier is a single-use or immutable request object, you don't need to
    * clear fields as they couldn't have been set before. If it is a mutable, retryable object,
    * successive calls should clear these fields first.
+   *
+   * @since 0.11
    */
   // The use cases of this are:
   // * allow pre-allocation of fields, especially in systems like gRPC Metadata
@@ -97,6 +101,7 @@ public abstract class TextFormat {
    * @param spanContext possibly not sampled.
    * @param carrier holds propagation fields. For example, an outgoing message or http request.
    * @param setter invoked for each propagation key to add or remove.
+   * @since 0.11
    */
   public abstract <C> void inject(SpanContext spanContext, C carrier, Setter<C> setter);
 
@@ -107,6 +112,7 @@ public abstract class TextFormat {
    * allocations.
    *
    * @param <C> carrier of propagation fields, such as an http request
+   * @since 0.11
    */
   public abstract static class Setter<C> {
 
@@ -119,6 +125,7 @@ public abstract class TextFormat {
      * @param carrier holds propagation fields. For example, an outgoing message or http request.
      * @param key the key of the field.
      * @param value the value of the field.
+     * @since 0.11
      */
     public abstract void put(C carrier, String key, String value);
   }
@@ -129,6 +136,7 @@ public abstract class TextFormat {
    * @param carrier holds propagation fields. For example, an outgoing message or http request.
    * @param getter invoked for each propagation key to get.
    * @throws SpanContextParseException if the input is invalid
+   * @since 0.11
    */
   public abstract <C> SpanContext extract(C carrier, Getter<C> getter)
       throws SpanContextParseException;
@@ -140,6 +148,7 @@ public abstract class TextFormat {
    * allocations.
    *
    * @param <C> carrier of propagation fields, such as an http request
+   * @since 0.11
    */
   public abstract static class Getter<C> {
 
@@ -149,6 +158,7 @@ public abstract class TextFormat {
      * @param carrier carrier of propagation fields, such as an http request
      * @param key the key of the field.
      * @return the first value of the given propagation {@code key} or returns {@code null}.
+     * @since 0.11
      */
     @Nullable
     public abstract String get(C carrier, String key);
diff --git a/api/src/main/java/io/opencensus/trace/samplers/Samplers.java b/api/src/main/java/io/opencensus/trace/samplers/Samplers.java
index 3d33a7f1..c10610a0 100644
--- a/api/src/main/java/io/opencensus/trace/samplers/Samplers.java
+++ b/api/src/main/java/io/opencensus/trace/samplers/Samplers.java
@@ -19,7 +19,11 @@ package io.opencensus.trace.samplers;
 import io.opencensus.trace.Sampler;
 import io.opencensus.trace.Span;
 
-/** Static class to access a set of pre-defined {@link Sampler Samplers}. */
+/**
+ * Static class to access a set of pre-defined {@link Sampler Samplers}.
+ *
+ * @since 0.5
+ */
 public final class Samplers {
   private static final Sampler ALWAYS_SAMPLE = new AlwaysSampleSampler();
   private static final Sampler NEVER_SAMPLE = new NeverSampleSampler();
@@ -31,6 +35,7 @@ public final class Samplers {
    * Returns a {@link Sampler} that always makes a "yes" decision on {@link Span} sampling.
    *
    * @return a {@code Sampler} that always makes a "yes" decision on {@code Span} sampling.
+   * @since 0.5
    */
   public static Sampler alwaysSample() {
     return ALWAYS_SAMPLE;
@@ -40,6 +45,7 @@ public final class Samplers {
    * Returns a {@link Sampler} that always makes a "no" decision on {@link Span} sampling.
    *
    * @return a {@code Sampler} that always makes a "no" decision on {@code Span} sampling.
+   * @since 0.5
    */
   public static Sampler neverSample() {
     return NEVER_SAMPLE;
@@ -51,6 +57,7 @@ public final class Samplers {
    * @param probability The desired probability of sampling. Must be within [0.0, 1.0].
    * @return a {@code Sampler} that makes a "yes" decision with a given probability.
    * @throws IllegalArgumentException if {@code probability} is out of range
+   * @since 0.5
    */
   public static Sampler probabilitySampler(double probability) {
     return ProbabilitySampler.create(probability);
diff --git a/api/src/main/java/io/opencensus/trace/unsafe/ContextUtils.java b/api/src/main/java/io/opencensus/trace/unsafe/ContextUtils.java
index cf0d2a65..f7905c25 100644
--- a/api/src/main/java/io/opencensus/trace/unsafe/ContextUtils.java
+++ b/api/src/main/java/io/opencensus/trace/unsafe/ContextUtils.java
@@ -24,11 +24,17 @@ import io.opencensus.trace.Span;
  *
  * <p>Users must interact with the current Context via the public APIs in {@link
  * io.opencensus.trace.Tracer} and avoid usages of the {@link #CONTEXT_SPAN_KEY} directly.
+ *
+ * @since 0.5
  */
 public final class ContextUtils {
   // No instance of this class.
   private ContextUtils() {}
 
-  /** The {@link io.grpc.Context.Key} used to interact with {@link io.grpc.Context}. */
+  /**
+   * The {@link io.grpc.Context.Key} used to interact with {@link io.grpc.Context}.
+   *
+   * @since 0.5
+   */
   public static final Context.Key<Span> CONTEXT_SPAN_KEY = Context.key("opencensus-trace-span-key");
 }