Rename NullnessUtils to CheckerFrameworkUtils.

16 files changed, 73 insertions, 56 deletions

diff --git a/api/src/main/java/io/opencensus/internal/NullnessUtils.java b/api/src/main/java/io/opencensus/internal/CheckerFrameworkUtils.java
index 0301b798..34f69b1e 100644
--- a/api/src/main/java/io/opencensus/internal/NullnessUtils.java
+++ b/api/src/main/java/io/opencensus/internal/CheckerFrameworkUtils.java
@@ -26,8 +26,8 @@ import org.checkerframework.checker.nullness.qual.KeyForBottom;
 /**
  * Utility methods for suppressing nullness warnings and working around Checker Framework issues.
  */
-public final class NullnessUtils {
-  private NullnessUtils() {}
+public final class CheckerFrameworkUtils {
+  private CheckerFrameworkUtils() {}
 
   /** Suppress warnings about a nullable value. */
   // TODO(sebright): Try to remove all uses of this method.
diff --git a/api/src/main/java/io/opencensus/stats/Aggregation.java b/api/src/main/java/io/opencensus/stats/Aggregation.java
index 7a612313..f9d2590c 100644
--- a/api/src/main/java/io/opencensus/stats/Aggregation.java
+++ b/api/src/main/java/io/opencensus/stats/Aggregation.java
@@ -20,7 +20,7 @@ import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.auto.value.AutoValue;
 import io.opencensus.common.Function;
-import io.opencensus.internal.NullnessUtils;
+import io.opencensus.internal.CheckerFrameworkUtils;
 import javax.annotation.concurrent.Immutable;
 
 /**
@@ -80,7 +80,7 @@ public abstract class Aggregation {
         Function<? super Mean, T> p2,
         Function<? super Distribution, T> p3,
         Function<? super Aggregation, T> defaultFunction) {
-      return NullnessUtils.<Sum, T>removeSuperFromFunctionParameterType(p0).apply(this);
+      return CheckerFrameworkUtils.<Sum, T>removeSuperFromFunctionParameterType(p0).apply(this);
     }
   }
 
@@ -112,7 +112,7 @@ public abstract class Aggregation {
         Function<? super Mean, T> p2,
         Function<? super Distribution, T> p3,
         Function<? super Aggregation, T> defaultFunction) {
-      return NullnessUtils.<Count, T>removeSuperFromFunctionParameterType(p1).apply(this);
+      return CheckerFrameworkUtils.<Count, T>removeSuperFromFunctionParameterType(p1).apply(this);
     }
   }
 
@@ -144,7 +144,7 @@ public abstract class Aggregation {
         Function<? super Mean, T> p2,
         Function<? super Distribution, T> p3,
         Function<? super Aggregation, T> defaultFunction) {
-      return NullnessUtils.<Mean, T>removeSuperFromFunctionParameterType(p2).apply(this);
+      return CheckerFrameworkUtils.<Mean, T>removeSuperFromFunctionParameterType(p2).apply(this);
     }
   }
 
@@ -180,7 +180,8 @@ public abstract class Aggregation {
         Function<? super Mean, T> p2,
         Function<? super Distribution, T> p3,
         Function<? super Aggregation, T> defaultFunction) {
-      return NullnessUtils.<Distribution, T>removeSuperFromFunctionParameterType(p3).apply(this);
+      return CheckerFrameworkUtils.<Distribution, T>removeSuperFromFunctionParameterType(p3)
+          .apply(this);
     }
   }
 }
diff --git a/api/src/main/java/io/opencensus/stats/AggregationData.java b/api/src/main/java/io/opencensus/stats/AggregationData.java
index bdf618bc..1ab7681c 100644
--- a/api/src/main/java/io/opencensus/stats/AggregationData.java
+++ b/api/src/main/java/io/opencensus/stats/AggregationData.java
@@ -22,7 +22,7 @@ import static com.google.common.base.Preconditions.checkNotNull;
 import com.google.auto.value.AutoValue;
 import com.google.common.collect.Lists;
 import io.opencensus.common.Function;
-import io.opencensus.internal.NullnessUtils;
+import io.opencensus.internal.CheckerFrameworkUtils;
 import java.util.Collections;
 import java.util.List;
 import javax.annotation.concurrent.Immutable;
@@ -93,7 +93,8 @@ public abstract class AggregationData {
         Function<? super MeanData, T> p3,
         Function<? super DistributionData, T> p4,
         Function<? super AggregationData, T> defaultFunction) {
-      return NullnessUtils.<SumDataDouble, T>removeSuperFromFunctionParameterType(p0).apply(this);
+      return CheckerFrameworkUtils.<SumDataDouble, T>removeSuperFromFunctionParameterType(p0)
+          .apply(this);
     }
   }
 
@@ -132,7 +133,8 @@ public abstract class AggregationData {
         Function<? super MeanData, T> p3,
         Function<? super DistributionData, T> p4,
         Function<? super AggregationData, T> defaultFunction) {
-      return NullnessUtils.<SumDataLong, T>removeSuperFromFunctionParameterType(p1).apply(this);
+      return CheckerFrameworkUtils.<SumDataLong, T>removeSuperFromFunctionParameterType(p1)
+          .apply(this);
     }
   }
 
@@ -171,7 +173,8 @@ public abstract class AggregationData {
         Function<? super MeanData, T> p3,
         Function<? super DistributionData, T> p4,
         Function<? super AggregationData, T> defaultFunction) {
-      return NullnessUtils.<CountData, T>removeSuperFromFunctionParameterType(p2).apply(this);
+      return CheckerFrameworkUtils.<CountData, T>removeSuperFromFunctionParameterType(p2)
+          .apply(this);
     }
   }
 
@@ -218,7 +221,8 @@ public abstract class AggregationData {
         Function<? super MeanData, T> p3,
         Function<? super DistributionData, T> p4,
         Function<? super AggregationData, T> defaultFunction) {
-      return NullnessUtils.<MeanData, T>removeSuperFromFunctionParameterType(p3).apply(this);
+      return CheckerFrameworkUtils.<MeanData, T>removeSuperFromFunctionParameterType(p3)
+          .apply(this);
     }
   }
 
@@ -318,7 +322,7 @@ public abstract class AggregationData {
         Function<? super MeanData, T> p3,
         Function<? super DistributionData, T> p4,
         Function<? super AggregationData, T> defaultFunction) {
-      return NullnessUtils.<DistributionData, T>removeSuperFromFunctionParameterType(p4)
+      return CheckerFrameworkUtils.<DistributionData, T>removeSuperFromFunctionParameterType(p4)
           .apply(this);
     }
   }
diff --git a/api/src/main/java/io/opencensus/stats/Measure.java b/api/src/main/java/io/opencensus/stats/Measure.java
index 70210f4e..b7b6c187 100644
--- a/api/src/main/java/io/opencensus/stats/Measure.java
+++ b/api/src/main/java/io/opencensus/stats/Measure.java
@@ -21,7 +21,7 @@ import static com.google.common.base.Preconditions.checkArgument;
 import com.google.auto.value.AutoValue;
 import com.google.common.annotations.VisibleForTesting;
 import io.opencensus.common.Function;
-import io.opencensus.internal.NullnessUtils;
+import io.opencensus.internal.CheckerFrameworkUtils;
 import io.opencensus.internal.StringUtil;
 import javax.annotation.concurrent.Immutable;
 
@@ -100,7 +100,8 @@ public abstract class Measure {
         Function<? super MeasureDouble, T> p0,
         Function<? super MeasureLong, T> p1,
         Function<? super Measure, T> defaultFunction) {
-      return NullnessUtils.<MeasureDouble, T>removeSuperFromFunctionParameterType(p0).apply(this);
+      return CheckerFrameworkUtils.<MeasureDouble, T>removeSuperFromFunctionParameterType(p0)
+          .apply(this);
     }
 
     @Override
@@ -145,7 +146,8 @@ public abstract class Measure {
         Function<? super MeasureDouble, T> p0,
         Function<? super MeasureLong, T> p1,
         Function<? super Measure, T> defaultFunction) {
-      return NullnessUtils.<MeasureLong, T>removeSuperFromFunctionParameterType(p1).apply(this);
+      return CheckerFrameworkUtils.<MeasureLong, T>removeSuperFromFunctionParameterType(p1)
+          .apply(this);
     }
 
     @Override
diff --git a/api/src/main/java/io/opencensus/stats/Measurement.java b/api/src/main/java/io/opencensus/stats/Measurement.java
index 954cf43a..2d9dcf02 100644
--- a/api/src/main/java/io/opencensus/stats/Measurement.java
+++ b/api/src/main/java/io/opencensus/stats/Measurement.java
@@ -18,7 +18,7 @@ package io.opencensus.stats;
 
 import com.google.auto.value.AutoValue;
 import io.opencensus.common.Function;
-import io.opencensus.internal.NullnessUtils;
+import io.opencensus.internal.CheckerFrameworkUtils;
 import io.opencensus.stats.Measure.MeasureDouble;
 import io.opencensus.stats.Measure.MeasureLong;
 import javax.annotation.concurrent.Immutable;
@@ -63,7 +63,7 @@ public abstract class Measurement {
         Function<? super MeasurementDouble, T> p0,
         Function<? super MeasurementLong, T> p1,
         Function<? super Measurement, T> defaultFunction) {
-      return NullnessUtils.<MeasurementDouble, T>removeSuperFromFunctionParameterType(p0)
+      return CheckerFrameworkUtils.<MeasurementDouble, T>removeSuperFromFunctionParameterType(p0)
           .apply(this);
     }
   }
@@ -92,7 +92,8 @@ public abstract class Measurement {
         Function<? super MeasurementDouble, T> p0,
         Function<? super MeasurementLong, T> p1,
         Function<? super Measurement, T> defaultFunction) {
-      return NullnessUtils.<MeasurementLong, T>removeSuperFromFunctionParameterType(p1).apply(this);
+      return CheckerFrameworkUtils.<MeasurementLong, T>removeSuperFromFunctionParameterType(p1)
+          .apply(this);
     }
   }
 }
diff --git a/api/src/main/java/io/opencensus/stats/Stats.java b/api/src/main/java/io/opencensus/stats/Stats.java
index 0830313a..18b1cf34 100644
--- a/api/src/main/java/io/opencensus/stats/Stats.java
+++ b/api/src/main/java/io/opencensus/stats/Stats.java
@@ -17,7 +17,7 @@
 package io.opencensus.stats;
 
 import com.google.common.annotations.VisibleForTesting;
-import io.opencensus.internal.NullnessUtils;
+import io.opencensus.internal.CheckerFrameworkUtils;
 import io.opencensus.internal.Provider;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -27,7 +27,7 @@ public final class Stats {
   private static final Logger logger = Logger.getLogger(Stats.class.getName());
 
   private static final StatsComponent statsComponent =
-      loadStatsComponent(NullnessUtils.castNonNull(StatsComponent.class.getClassLoader()));
+      loadStatsComponent(CheckerFrameworkUtils.castNonNull(StatsComponent.class.getClassLoader()));
 
   /** Returns the default {@link StatsRecorder}. */
   public static StatsRecorder getStatsRecorder() {
diff --git a/api/src/main/java/io/opencensus/stats/View.java b/api/src/main/java/io/opencensus/stats/View.java
index 4f852c77..0ab29e5e 100644
--- a/api/src/main/java/io/opencensus/stats/View.java
+++ b/api/src/main/java/io/opencensus/stats/View.java
@@ -22,7 +22,7 @@ import com.google.auto.value.AutoValue;
 import com.google.common.annotations.VisibleForTesting;
 import io.opencensus.common.Duration;
 import io.opencensus.common.Function;
-import io.opencensus.internal.NullnessUtils;
+import io.opencensus.internal.CheckerFrameworkUtils;
 import io.opencensus.internal.StringUtil;
 import io.opencensus.tags.TagKey;
 import java.util.ArrayList;
@@ -179,7 +179,8 @@ public abstract class View {
           Function<? super Cumulative, T> p0,
           Function<? super Interval, T> p1,
           Function<? super AggregationWindow, T> defaultFunction) {
-        return NullnessUtils.<Cumulative, T>removeSuperFromFunctionParameterType(p0).apply(this);
+        return CheckerFrameworkUtils.<Cumulative, T>removeSuperFromFunctionParameterType(p0)
+            .apply(this);
       }
     }
 
@@ -221,7 +222,8 @@ public abstract class View {
           Function<? super Cumulative, T> p0,
           Function<? super Interval, T> p1,
           Function<? super AggregationWindow, T> defaultFunction) {
-        return NullnessUtils.<Interval, T>removeSuperFromFunctionParameterType(p1).apply(this);
+        return CheckerFrameworkUtils.<Interval, T>removeSuperFromFunctionParameterType(p1)
+            .apply(this);
       }
     }
   }
diff --git a/api/src/main/java/io/opencensus/stats/ViewData.java b/api/src/main/java/io/opencensus/stats/ViewData.java
index fe2510bc..f383fff5 100644
--- a/api/src/main/java/io/opencensus/stats/ViewData.java
+++ b/api/src/main/java/io/opencensus/stats/ViewData.java
@@ -23,7 +23,7 @@ import com.google.common.collect.Maps;
 import io.opencensus.common.Function;
 import io.opencensus.common.Functions;
 import io.opencensus.common.Timestamp;
-import io.opencensus.internal.NullnessUtils;
+import io.opencensus.internal.CheckerFrameworkUtils;
 import io.opencensus.stats.Aggregation.Count;
 import io.opencensus.stats.Aggregation.Distribution;
 import io.opencensus.stats.Aggregation.Mean;
@@ -242,7 +242,7 @@ public abstract class ViewData {
           Function<? super CumulativeData, T> p0,
           Function<? super IntervalData, T> p1,
           Function<? super AggregationWindowData, T> defaultFunction) {
-        return NullnessUtils.<CumulativeData, T>removeSuperFromFunctionParameterType(p0)
+        return CheckerFrameworkUtils.<CumulativeData, T>removeSuperFromFunctionParameterType(p0)
             .apply(this);
       }
 
@@ -277,7 +277,8 @@ public abstract class ViewData {
           Function<? super CumulativeData, T> p0,
           Function<? super IntervalData, T> p1,
           Function<? super AggregationWindowData, T> defaultFunction) {
-        return NullnessUtils.<IntervalData, T>removeSuperFromFunctionParameterType(p1).apply(this);
+        return CheckerFrameworkUtils.<IntervalData, T>removeSuperFromFunctionParameterType(p1)
+            .apply(this);
       }
 
       /** Constructs a new {@link IntervalData}. */
diff --git a/api/src/main/java/io/opencensus/tags/Tags.java b/api/src/main/java/io/opencensus/tags/Tags.java
index f480714d..b2162264 100644
--- a/api/src/main/java/io/opencensus/tags/Tags.java
+++ b/api/src/main/java/io/opencensus/tags/Tags.java
@@ -17,7 +17,7 @@
 package io.opencensus.tags;
 
 import com.google.common.annotations.VisibleForTesting;
-import io.opencensus.internal.NullnessUtils;
+import io.opencensus.internal.CheckerFrameworkUtils;
 import io.opencensus.internal.Provider;
 import io.opencensus.tags.propagation.TagPropagationComponent;
 import java.util.logging.Level;
@@ -28,7 +28,7 @@ public final class Tags {
   private static final Logger logger = Logger.getLogger(Tags.class.getName());
 
   private static final TagsComponent tagsComponent =
-      loadTagsComponent(NullnessUtils.castNonNull(TagsComponent.class.getClassLoader()));
+      loadTagsComponent(CheckerFrameworkUtils.castNonNull(TagsComponent.class.getClassLoader()));
 
   private Tags() {}
 
diff --git a/api/src/main/java/io/opencensus/trace/AttributeValue.java b/api/src/main/java/io/opencensus/trace/AttributeValue.java
index 2de8fc91..619d94ad 100644
--- a/api/src/main/java/io/opencensus/trace/AttributeValue.java
+++ b/api/src/main/java/io/opencensus/trace/AttributeValue.java
@@ -20,7 +20,7 @@ import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.auto.value.AutoValue;
 import io.opencensus.common.Function;
-import io.opencensus.internal.NullnessUtils;
+import io.opencensus.internal.CheckerFrameworkUtils;
 import javax.annotation.concurrent.Immutable;
 
 /**
@@ -101,7 +101,7 @@ public abstract class AttributeValue {
         Function<? super Boolean, T> booleanFunction,
         Function<? super Long, T> longFunction,
         Function<Object, T> defaultFunction) {
-      return NullnessUtils.<String, T>removeSuperFromFunctionParameterType(stringFunction)
+      return CheckerFrameworkUtils.<String, T>removeSuperFromFunctionParameterType(stringFunction)
           .apply(getStringValue());
     }
 
@@ -128,7 +128,7 @@ public abstract class AttributeValue {
         Function<? super Boolean, T> booleanFunction,
         Function<? super Long, T> longFunction,
         Function<Object, T> defaultFunction) {
-      return NullnessUtils.<Boolean, T>removeSuperFromFunctionParameterType(booleanFunction)
+      return CheckerFrameworkUtils.<Boolean, T>removeSuperFromFunctionParameterType(booleanFunction)
           .apply(getBooleanValue());
     }
 
@@ -155,7 +155,7 @@ public abstract class AttributeValue {
         Function<? super Boolean, T> booleanFunction,
         Function<? super Long, T> longFunction,
         Function<Object, T> defaultFunction) {
-      return NullnessUtils.<Long, T>removeSuperFromFunctionParameterType(longFunction)
+      return CheckerFrameworkUtils.<Long, T>removeSuperFromFunctionParameterType(longFunction)
           .apply(getLongValue());
     }
 
diff --git a/api/src/main/java/io/opencensus/trace/Tracing.java b/api/src/main/java/io/opencensus/trace/Tracing.java
index 8e575265..ba79fd08 100644
--- a/api/src/main/java/io/opencensus/trace/Tracing.java
+++ b/api/src/main/java/io/opencensus/trace/Tracing.java
@@ -18,7 +18,7 @@ package io.opencensus.trace;
 
 import com.google.common.annotations.VisibleForTesting;
 import io.opencensus.common.Clock;
-import io.opencensus.internal.NullnessUtils;
+import io.opencensus.internal.CheckerFrameworkUtils;
 import io.opencensus.internal.Provider;
 import io.opencensus.trace.config.TraceConfig;
 import io.opencensus.trace.export.ExportComponent;
@@ -30,7 +30,7 @@ import java.util.logging.Logger;
 public final class Tracing {
   private static final Logger logger = Logger.getLogger(Tracing.class.getName());
   private static final TraceComponent traceComponent =
-      loadTraceComponent(NullnessUtils.castNonNull(TraceComponent.class.getClassLoader()));
+      loadTraceComponent(CheckerFrameworkUtils.castNonNull(TraceComponent.class.getClassLoader()));
 
   /**
    * Returns the global {@link Tracer}.
diff --git a/impl_core/src/main/java/io/opencensus/implcore/internal/NullnessUtils.java b/impl_core/src/main/java/io/opencensus/implcore/internal/CheckerFrameworkUtils.java
index 3d2d4d15..4d5f9c4d 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/internal/NullnessUtils.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/internal/CheckerFrameworkUtils.java
@@ -26,8 +26,8 @@ import org.checkerframework.checker.nullness.qual.KeyForBottom;
 /**
  * Utility methods for suppressing nullness warnings and working around Checker Framework issues.
  */
-public final class NullnessUtils {
-  private NullnessUtils() {}
+public final class CheckerFrameworkUtils {
+  private CheckerFrameworkUtils() {}
 
   /** Suppress warnings about a nullable value. */
   // TODO(sebright): Try to remove all uses of this method.
diff --git a/impl_core/src/main/java/io/opencensus/implcore/stats/MutableAggregation.java b/impl_core/src/main/java/io/opencensus/implcore/stats/MutableAggregation.java
index 1a5771eb..49124b00 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/stats/MutableAggregation.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/stats/MutableAggregation.java
@@ -20,7 +20,7 @@ import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import io.opencensus.common.Function;
-import io.opencensus.implcore.internal.NullnessUtils;
+import io.opencensus.implcore.internal.CheckerFrameworkUtils;
 import io.opencensus.stats.Aggregation;
 import io.opencensus.stats.BucketBoundaries;
 
@@ -100,7 +100,8 @@ abstract class MutableAggregation {
         Function<? super MutableCount, T> p1,
         Function<? super MutableMean, T> p2,
         Function<? super MutableDistribution, T> p3) {
-      return NullnessUtils.<MutableSum, T>removeSuperFromFunctionParameterType(p0).apply(this);
+      return CheckerFrameworkUtils.<MutableSum, T>removeSuperFromFunctionParameterType(p0)
+          .apply(this);
     }
   }
 
@@ -146,7 +147,8 @@ abstract class MutableAggregation {
         Function<? super MutableCount, T> p1,
         Function<? super MutableMean, T> p2,
         Function<? super MutableDistribution, T> p3) {
-      return NullnessUtils.<MutableCount, T>removeSuperFromFunctionParameterType(p1).apply(this);
+      return CheckerFrameworkUtils.<MutableCount, T>removeSuperFromFunctionParameterType(p1)
+          .apply(this);
     }
   }
 
@@ -214,7 +216,8 @@ abstract class MutableAggregation {
         Function<? super MutableCount, T> p1,
         Function<? super MutableMean, T> p2,
         Function<? super MutableDistribution, T> p3) {
-      return NullnessUtils.<MutableMean, T>removeSuperFromFunctionParameterType(p2).apply(this);
+      return CheckerFrameworkUtils.<MutableMean, T>removeSuperFromFunctionParameterType(p2)
+          .apply(this);
     }
   }
 
@@ -356,7 +359,7 @@ abstract class MutableAggregation {
         Function<? super MutableCount, T> p1,
         Function<? super MutableMean, T> p2,
         Function<? super MutableDistribution, T> p3) {
-      return NullnessUtils.<MutableDistribution, T>removeSuperFromFunctionParameterType(p3)
+      return CheckerFrameworkUtils.<MutableDistribution, T>removeSuperFromFunctionParameterType(p3)
           .apply(this);
     }
   }
diff --git a/impl_core/src/main/java/io/opencensus/implcore/stats/MutableViewData.java b/impl_core/src/main/java/io/opencensus/implcore/stats/MutableViewData.java
index 4963ce59..8ecb7dca 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/stats/MutableViewData.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/stats/MutableViewData.java
@@ -26,7 +26,7 @@ import io.opencensus.common.Duration;
 import io.opencensus.common.Function;
 import io.opencensus.common.Functions;
 import io.opencensus.common.Timestamp;
-import io.opencensus.implcore.internal.NullnessUtils;
+import io.opencensus.implcore.internal.CheckerFrameworkUtils;
 import io.opencensus.implcore.stats.MutableAggregation.MutableCount;
 import io.opencensus.implcore.stats.MutableAggregation.MutableDistribution;
 import io.opencensus.implcore.stats.MutableAggregation.MutableMean;
@@ -313,7 +313,7 @@ abstract class MutableViewData {
           getTagValues(getTagMap(context), super.view.getColumns());
       refreshBucketList(timestamp);
       // It is always the last bucket that does the recording.
-      NullnessUtils.castNonNull(buckets.peekLast()).record(tagValues, value);
+      CheckerFrameworkUtils.castNonNull(buckets.peekLast()).record(tagValues, value);
     }
 
     @Override
@@ -351,7 +351,8 @@ abstract class MutableViewData {
       if (buckets.size() != N + 1) {
         throw new AssertionError("Bucket list must have exactly " + (N + 1) + " buckets.");
       }
-      Timestamp startOfLastBucket = NullnessUtils.castNonNull(buckets.peekLast()).getStart();
+      Timestamp startOfLastBucket =
+          CheckerFrameworkUtils.castNonNull(buckets.peekLast()).getStart();
       // TODO(songya): decide what to do when time goes backwards
       checkArgument(
           now.compareTo(startOfLastBucket) >= 0,
@@ -368,7 +369,9 @@ abstract class MutableViewData {
 
       if (!buckets.isEmpty()) {
         startOfNewBucket =
-            NullnessUtils.castNonNull(buckets.peekLast()).getStart().addDuration(bucketDuration);
+            CheckerFrameworkUtils.castNonNull(buckets.peekLast())
+                .getStart()
+                .addDuration(bucketDuration);
       } else {
         // Initialize bucket list. Should only enter this block once.
         startOfNewBucket = subtractDuration(now, totalDuration);
@@ -418,8 +421,8 @@ abstract class MutableViewData {
         Aggregation aggregation,
         Timestamp now) {
       // Put fractional stats of the head (oldest) bucket.
-      IntervalBucket head = NullnessUtils.castNonNull(buckets.peekFirst());
-      IntervalBucket tail = NullnessUtils.castNonNull(buckets.peekLast());
+      IntervalBucket head = CheckerFrameworkUtils.castNonNull(buckets.peekFirst());
+      IntervalBucket tail = CheckerFrameworkUtils.castNonNull(buckets.peekLast());
       double fractionTail = tail.getFraction(now);
       // TODO(songya): decide what to do when time goes backwards
       checkArgument(
diff --git a/impl_core/src/main/java/io/opencensus/implcore/trace/SpanImpl.java b/impl_core/src/main/java/io/opencensus/implcore/trace/SpanImpl.java
index f80ba2bf..8ce863e7 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/trace/SpanImpl.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/trace/SpanImpl.java
@@ -22,7 +22,7 @@ import static com.google.common.base.Preconditions.checkState;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.EvictingQueue;
 import io.opencensus.common.Clock;
-import io.opencensus.implcore.internal.NullnessUtils;
+import io.opencensus.implcore.internal.CheckerFrameworkUtils;
 import io.opencensus.implcore.internal.TimestampConverter;
 import io.opencensus.implcore.trace.internal.ConcurrentIntrusiveList.Element;
 import io.opencensus.trace.Annotation;
@@ -250,7 +250,7 @@ public final class SpanImpl extends Span implements Element<SpanImpl> {
           parentSpanId,
           hasRemoteParent,
           name,
-          NullnessUtils.castNonNull(timestampConverter).convertNanoTime(startNanoTime),
+          CheckerFrameworkUtils.castNonNull(timestampConverter).convertNanoTime(startNanoTime),
           attributesSpanData,
           annotationsSpanData,
           networkEventsSpanData,
@@ -258,7 +258,7 @@ public final class SpanImpl extends Span implements Element<SpanImpl> {
           null, // Not supported yet.
           hasBeenEnded ? getStatusWithDefault() : null,
           hasBeenEnded
-              ? NullnessUtils.castNonNull(timestampConverter).convertNanoTime(endNanoTime)
+              ? CheckerFrameworkUtils.castNonNull(timestampConverter).convertNanoTime(endNanoTime)
               : null);
     }
   }
@@ -439,7 +439,7 @@ public final class SpanImpl extends Span implements Element<SpanImpl> {
     List<TimedEvent<T>> eventsList = new ArrayList<TimedEvent<T>>(events.events.size());
     for (EventWithNanoTime<T> networkEvent : events.events) {
       eventsList.add(
-          networkEvent.toSpanDataTimedEvent(NullnessUtils.castNonNull(timestampConverter)));
+          networkEvent.toSpanDataTimedEvent(CheckerFrameworkUtils.castNonNull(timestampConverter)));
     }
     return SpanData.TimedEvents.create(eventsList, events.getNumberOfDroppedEvents());
   }
diff --git a/impl_core/src/main/java/io/opencensus/implcore/trace/internal/ConcurrentIntrusiveList.java b/impl_core/src/main/java/io/opencensus/implcore/trace/internal/ConcurrentIntrusiveList.java
index 5b131756..22d8e41a 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/trace/internal/ConcurrentIntrusiveList.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/trace/internal/ConcurrentIntrusiveList.java
@@ -18,7 +18,7 @@ package io.opencensus.implcore.trace.internal;
 
 import static com.google.common.base.Preconditions.checkArgument;
 
-import io.opencensus.implcore.internal.NullnessUtils;
+import io.opencensus.implcore.internal.CheckerFrameworkUtils;
 import io.opencensus.implcore.trace.internal.ConcurrentIntrusiveList.Element;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -108,11 +108,11 @@ public final class ConcurrentIntrusiveList<T extends Element<T>> {
     } else if (element.getNext() == null) {
       // This is the last element, and there is at least another element because
       // element.getPrev() != null.
-      NullnessUtils.castNonNull(element.getPrev()).setNext(null);
+      CheckerFrameworkUtils.castNonNull(element.getPrev()).setNext(null);
       element.setPrev(null);
     } else {
-      NullnessUtils.castNonNull(element.getPrev()).setNext(element.getNext());
-      NullnessUtils.castNonNull(element.getNext()).setPrev(element.getPrev());
+      CheckerFrameworkUtils.castNonNull(element.getPrev()).setNext(element.getNext());
+      CheckerFrameworkUtils.castNonNull(element.getNext()).setPrev(element.getPrev());
       element.setNext(null);
       element.setPrev(null);
     }