Mode classes for metrics data model in the exporter package. (#1480)

* Mode classes for metrics data model in the exporter package. Consistent with trace.

* Fix test class coments.

33 files changed, 85 insertions, 80 deletions

diff --git a/api/src/main/java/io/opencensus/metrics/MetricRegistry.java b/api/src/main/java/io/opencensus/metrics/MetricRegistry.java
index c249d47b..a9987b75 100644
--- a/api/src/main/java/io/opencensus/metrics/MetricRegistry.java
+++ b/api/src/main/java/io/opencensus/metrics/MetricRegistry.java
@@ -24,7 +24,7 @@ import java.util.LinkedHashMap;
 
 /**
  * Creates and manages your application's set of metrics. The default implementation of this creates
- * a {@link MetricProducer} and registers it to the global {@link
+ * a {@link io.opencensus.metrics.export.MetricProducer} and registers it to the global {@link
  * io.opencensus.metrics.export.MetricProducerManager}.
  *
  * @since 0.17
diff --git a/api/src/main/java/io/opencensus/metrics/Distribution.java b/api/src/main/java/io/opencensus/metrics/export/Distribution.java
index 9294b838..dc9fa9e9 100644
--- a/api/src/main/java/io/opencensus/metrics/Distribution.java
+++ b/api/src/main/java/io/opencensus/metrics/export/Distribution.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import com.google.auto.value.AutoValue;
 import io.opencensus.common.ExperimentalApi;
diff --git a/api/src/main/java/io/opencensus/metrics/Metric.java b/api/src/main/java/io/opencensus/metrics/export/Metric.java
index 0c108b56..07fe356a 100644
--- a/api/src/main/java/io/opencensus/metrics/Metric.java
+++ b/api/src/main/java/io/opencensus/metrics/export/Metric.java
@@ -14,15 +14,15 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import com.google.auto.value.AutoValue;
 import io.opencensus.common.ExperimentalApi;
 import io.opencensus.internal.Utils;
-import io.opencensus.metrics.Value.ValueDistribution;
-import io.opencensus.metrics.Value.ValueDouble;
-import io.opencensus.metrics.Value.ValueLong;
-import io.opencensus.metrics.Value.ValueSummary;
+import io.opencensus.metrics.export.Value.ValueDistribution;
+import io.opencensus.metrics.export.Value.ValueDouble;
+import io.opencensus.metrics.export.Value.ValueLong;
+import io.opencensus.metrics.export.Value.ValueSummary;
 import java.util.List;
 import javax.annotation.concurrent.Immutable;
 
diff --git a/api/src/main/java/io/opencensus/metrics/MetricDescriptor.java b/api/src/main/java/io/opencensus/metrics/export/MetricDescriptor.java
index 5146cd85..a4629f8e 100644
--- a/api/src/main/java/io/opencensus/metrics/MetricDescriptor.java
+++ b/api/src/main/java/io/opencensus/metrics/export/MetricDescriptor.java
@@ -14,11 +14,12 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import com.google.auto.value.AutoValue;
 import io.opencensus.common.ExperimentalApi;
 import io.opencensus.internal.Utils;
+import io.opencensus.metrics.LabelKey;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
diff --git a/api/src/main/java/io/opencensus/metrics/MetricProducer.java b/api/src/main/java/io/opencensus/metrics/export/MetricProducer.java
index 86f9732f..739a0a9f 100644
--- a/api/src/main/java/io/opencensus/metrics/MetricProducer.java
+++ b/api/src/main/java/io/opencensus/metrics/export/MetricProducer.java
@@ -14,10 +14,9 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import io.opencensus.common.ExperimentalApi;
-import io.opencensus.metrics.export.MetricProducerManager;
 import java.util.Collection;
 
 /**
diff --git a/api/src/main/java/io/opencensus/metrics/export/MetricProducerManager.java b/api/src/main/java/io/opencensus/metrics/export/MetricProducerManager.java
index fc864200..304d9294 100644
--- a/api/src/main/java/io/opencensus/metrics/export/MetricProducerManager.java
+++ b/api/src/main/java/io/opencensus/metrics/export/MetricProducerManager.java
@@ -18,7 +18,6 @@ package io.opencensus.metrics.export;
 
 import io.opencensus.common.ExperimentalApi;
 import io.opencensus.internal.Utils;
-import io.opencensus.metrics.MetricProducer;
 import java.util.Collections;
 import java.util.Set;
 import javax.annotation.concurrent.ThreadSafe;
diff --git a/api/src/main/java/io/opencensus/metrics/Point.java b/api/src/main/java/io/opencensus/metrics/export/Point.java
index 9ef7c15b..1f382f9b 100644
--- a/api/src/main/java/io/opencensus/metrics/Point.java
+++ b/api/src/main/java/io/opencensus/metrics/export/Point.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import com.google.auto.value.AutoValue;
 import io.opencensus.common.ExperimentalApi;
diff --git a/api/src/main/java/io/opencensus/metrics/Summary.java b/api/src/main/java/io/opencensus/metrics/export/Summary.java
index f23667bb..c82ca961 100644
--- a/api/src/main/java/io/opencensus/metrics/Summary.java
+++ b/api/src/main/java/io/opencensus/metrics/export/Summary.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import com.google.auto.value.AutoValue;
 import io.opencensus.common.ExperimentalApi;
diff --git a/api/src/main/java/io/opencensus/metrics/TimeSeries.java b/api/src/main/java/io/opencensus/metrics/export/TimeSeries.java
index d504dad9..959f55ba 100644
--- a/api/src/main/java/io/opencensus/metrics/TimeSeries.java
+++ b/api/src/main/java/io/opencensus/metrics/export/TimeSeries.java
@@ -14,12 +14,14 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import com.google.auto.value.AutoValue;
 import io.opencensus.common.ExperimentalApi;
 import io.opencensus.common.Timestamp;
 import io.opencensus.internal.Utils;
+import io.opencensus.metrics.LabelKey;
+import io.opencensus.metrics.LabelValue;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
diff --git a/api/src/main/java/io/opencensus/metrics/Value.java b/api/src/main/java/io/opencensus/metrics/export/Value.java
index 1bc63b79..00a939c0 100644
--- a/api/src/main/java/io/opencensus/metrics/Value.java
+++ b/api/src/main/java/io/opencensus/metrics/export/Value.java
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import com.google.auto.value.AutoValue;
 import io.opencensus.common.ExperimentalApi;
diff --git a/api/src/test/java/io/opencensus/metrics/DistributionTest.java b/api/src/test/java/io/opencensus/metrics/export/DistributionTest.java
index 5ee88dd6..0be4b5d1 100644
--- a/api/src/test/java/io/opencensus/metrics/DistributionTest.java
+++ b/api/src/test/java/io/opencensus/metrics/export/DistributionTest.java
@@ -14,14 +14,14 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.testing.EqualsTester;
 import io.opencensus.common.Timestamp;
-import io.opencensus.metrics.Distribution.Bucket;
-import io.opencensus.metrics.Distribution.Exemplar;
+import io.opencensus.metrics.export.Distribution.Bucket;
+import io.opencensus.metrics.export.Distribution.Exemplar;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
diff --git a/api/src/test/java/io/opencensus/metrics/MetricDescriptorTest.java b/api/src/test/java/io/opencensus/metrics/export/MetricDescriptorTest.java
index 9c0a42fc..502170c6 100644
--- a/api/src/test/java/io/opencensus/metrics/MetricDescriptorTest.java
+++ b/api/src/test/java/io/opencensus/metrics/export/MetricDescriptorTest.java
@@ -14,12 +14,13 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.testing.EqualsTester;
-import io.opencensus.metrics.MetricDescriptor.Type;
+import io.opencensus.metrics.LabelKey;
+import io.opencensus.metrics.export.MetricDescriptor.Type;
 import java.util.Arrays;
 import java.util.List;
 import org.hamcrest.CoreMatchers;
diff --git a/api/src/test/java/io/opencensus/metrics/export/MetricProducerManagerTest.java b/api/src/test/java/io/opencensus/metrics/export/MetricProducerManagerTest.java
index 07854927..1025427f 100644
--- a/api/src/test/java/io/opencensus/metrics/export/MetricProducerManagerTest.java
+++ b/api/src/test/java/io/opencensus/metrics/export/MetricProducerManagerTest.java
@@ -18,7 +18,6 @@ package io.opencensus.metrics.export;
 
 import static com.google.common.truth.Truth.assertThat;
 
-import io.opencensus.metrics.MetricProducer;
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
diff --git a/api/src/test/java/io/opencensus/metrics/MetricTest.java b/api/src/test/java/io/opencensus/metrics/export/MetricTest.java
index 37deed4b..0b1ecf65 100644
--- a/api/src/test/java/io/opencensus/metrics/MetricTest.java
+++ b/api/src/test/java/io/opencensus/metrics/export/MetricTest.java
@@ -14,13 +14,15 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.testing.EqualsTester;
 import io.opencensus.common.Timestamp;
-import io.opencensus.metrics.MetricDescriptor.Type;
+import io.opencensus.metrics.LabelKey;
+import io.opencensus.metrics.LabelValue;
+import io.opencensus.metrics.export.MetricDescriptor.Type;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
diff --git a/api/src/test/java/io/opencensus/metrics/PointTest.java b/api/src/test/java/io/opencensus/metrics/export/PointTest.java
index 708814c5..da5b83dc 100644
--- a/api/src/test/java/io/opencensus/metrics/PointTest.java
+++ b/api/src/test/java/io/opencensus/metrics/export/PointTest.java
@@ -14,13 +14,13 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.testing.EqualsTester;
 import io.opencensus.common.Timestamp;
-import io.opencensus.metrics.Distribution.Bucket;
+import io.opencensus.metrics.export.Distribution.Bucket;
 import java.util.Arrays;
 import org.junit.Test;
 import org.junit.runner.RunWith;
diff --git a/api/src/test/java/io/opencensus/metrics/SummaryTest.java b/api/src/test/java/io/opencensus/metrics/export/SummaryTest.java
index 0b70d94e..c10df043 100644
--- a/api/src/test/java/io/opencensus/metrics/SummaryTest.java
+++ b/api/src/test/java/io/opencensus/metrics/export/SummaryTest.java
@@ -14,13 +14,13 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.testing.EqualsTester;
-import io.opencensus.metrics.Summary.Snapshot;
-import io.opencensus.metrics.Summary.Snapshot.ValueAtPercentile;
+import io.opencensus.metrics.export.Summary.Snapshot;
+import io.opencensus.metrics.export.Summary.Snapshot.ValueAtPercentile;
 import java.util.Collections;
 import org.junit.Rule;
 import org.junit.Test;
diff --git a/api/src/test/java/io/opencensus/metrics/TimeSeriesTest.java b/api/src/test/java/io/opencensus/metrics/export/TimeSeriesTest.java
index 07dff97d..31812549 100644
--- a/api/src/test/java/io/opencensus/metrics/TimeSeriesTest.java
+++ b/api/src/test/java/io/opencensus/metrics/export/TimeSeriesTest.java
@@ -14,12 +14,13 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.testing.EqualsTester;
 import io.opencensus.common.Timestamp;
+import io.opencensus.metrics.LabelValue;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
diff --git a/api/src/test/java/io/opencensus/metrics/ValueTest.java b/api/src/test/java/io/opencensus/metrics/export/ValueTest.java
index a65202a8..3758ed2d 100644
--- a/api/src/test/java/io/opencensus/metrics/ValueTest.java
+++ b/api/src/test/java/io/opencensus/metrics/export/ValueTest.java
@@ -14,20 +14,20 @@
  * limitations under the License.
  */
 
-package io.opencensus.metrics;
+package io.opencensus.metrics.export;
 
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.testing.EqualsTester;
 import io.opencensus.common.Function;
 import io.opencensus.common.Functions;
-import io.opencensus.metrics.Distribution.Bucket;
-import io.opencensus.metrics.Summary.Snapshot;
-import io.opencensus.metrics.Summary.Snapshot.ValueAtPercentile;
-import io.opencensus.metrics.Value.ValueDistribution;
-import io.opencensus.metrics.Value.ValueDouble;
-import io.opencensus.metrics.Value.ValueLong;
-import io.opencensus.metrics.Value.ValueSummary;
+import io.opencensus.metrics.export.Distribution.Bucket;
+import io.opencensus.metrics.export.Summary.Snapshot;
+import io.opencensus.metrics.export.Summary.Snapshot.ValueAtPercentile;
+import io.opencensus.metrics.export.Value.ValueDistribution;
+import io.opencensus.metrics.export.Value.ValueDouble;
+import io.opencensus.metrics.export.Value.ValueLong;
+import io.opencensus.metrics.export.Value.ValueSummary;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
diff --git a/impl_core/src/main/java/io/opencensus/implcore/metrics/Gauge.java b/impl_core/src/main/java/io/opencensus/implcore/metrics/Gauge.java
index e6498066..30e5bf36 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/metrics/Gauge.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/metrics/Gauge.java
@@ -23,12 +23,12 @@ import io.opencensus.common.ToDoubleFunction;
 import io.opencensus.common.ToLongFunction;
 import io.opencensus.metrics.LabelKey;
 import io.opencensus.metrics.LabelValue;
-import io.opencensus.metrics.Metric;
-import io.opencensus.metrics.MetricDescriptor;
-import io.opencensus.metrics.MetricDescriptor.Type;
-import io.opencensus.metrics.Point;
-import io.opencensus.metrics.TimeSeries;
-import io.opencensus.metrics.Value;
+import io.opencensus.metrics.export.Metric;
+import io.opencensus.metrics.export.MetricDescriptor;
+import io.opencensus.metrics.export.MetricDescriptor.Type;
+import io.opencensus.metrics.export.Point;
+import io.opencensus.metrics.export.TimeSeries;
+import io.opencensus.metrics.export.Value;
 import java.util.Collections;
 import java.util.List;
 
diff --git a/impl_core/src/main/java/io/opencensus/implcore/metrics/MetricRegistryImpl.java b/impl_core/src/main/java/io/opencensus/implcore/metrics/MetricRegistryImpl.java
index 642a9515..3a30fd38 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/metrics/MetricRegistryImpl.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/metrics/MetricRegistryImpl.java
@@ -25,9 +25,9 @@ import io.opencensus.implcore.metrics.Gauge.DoubleGauge;
 import io.opencensus.implcore.metrics.Gauge.LongGauge;
 import io.opencensus.metrics.LabelKey;
 import io.opencensus.metrics.LabelValue;
-import io.opencensus.metrics.Metric;
-import io.opencensus.metrics.MetricProducer;
 import io.opencensus.metrics.MetricRegistry;
+import io.opencensus.metrics.export.Metric;
+import io.opencensus.metrics.export.MetricProducer;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
diff --git a/impl_core/src/main/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImpl.java b/impl_core/src/main/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImpl.java
index fc9db5c1..6f585a10 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImpl.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImpl.java
@@ -17,7 +17,7 @@
 package io.opencensus.implcore.metrics.export;
 
 import com.google.common.base.Preconditions;
-import io.opencensus.metrics.MetricProducer;
+import io.opencensus.metrics.export.MetricProducer;
 import io.opencensus.metrics.export.MetricProducerManager;
 import java.util.Collections;
 import java.util.LinkedHashSet;
diff --git a/impl_core/src/main/java/io/opencensus/implcore/stats/MeasureToViewMap.java b/impl_core/src/main/java/io/opencensus/implcore/stats/MeasureToViewMap.java
index 2e28991c..5da0cad8 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/stats/MeasureToViewMap.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/stats/MeasureToViewMap.java
@@ -23,7 +23,7 @@ import com.google.common.collect.Sets;
 import io.opencensus.common.Clock;
 import io.opencensus.common.Timestamp;
 import io.opencensus.implcore.internal.CurrentState.State;
-import io.opencensus.metrics.Metric;
+import io.opencensus.metrics.export.Metric;
 import io.opencensus.stats.Measure;
 import io.opencensus.stats.Measurement;
 import io.opencensus.stats.View;
diff --git a/impl_core/src/main/java/io/opencensus/implcore/stats/MetricProducerImpl.java b/impl_core/src/main/java/io/opencensus/implcore/stats/MetricProducerImpl.java
index 31ef6be1..7bf92572 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/stats/MetricProducerImpl.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/stats/MetricProducerImpl.java
@@ -16,8 +16,8 @@
 
 package io.opencensus.implcore.stats;
 
-import io.opencensus.metrics.Metric;
-import io.opencensus.metrics.MetricProducer;
+import io.opencensus.metrics.export.Metric;
+import io.opencensus.metrics.export.MetricProducer;
 import java.util.Collection;
 import javax.annotation.concurrent.ThreadSafe;
 
diff --git a/impl_core/src/main/java/io/opencensus/implcore/stats/MetricUtils.java b/impl_core/src/main/java/io/opencensus/implcore/stats/MetricUtils.java
index cd1e5364..0dfb1d26 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/stats/MetricUtils.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/stats/MetricUtils.java
@@ -21,8 +21,8 @@ import io.opencensus.common.Function;
 import io.opencensus.common.Functions;
 import io.opencensus.metrics.LabelKey;
 import io.opencensus.metrics.LabelValue;
-import io.opencensus.metrics.MetricDescriptor;
-import io.opencensus.metrics.MetricDescriptor.Type;
+import io.opencensus.metrics.export.MetricDescriptor;
+import io.opencensus.metrics.export.MetricDescriptor.Type;
 import io.opencensus.stats.Aggregation;
 import io.opencensus.stats.Measure;
 import io.opencensus.stats.View;
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 eaf440ff..83beaea7 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
@@ -21,9 +21,9 @@ import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.annotations.VisibleForTesting;
 import io.opencensus.common.Timestamp;
-import io.opencensus.metrics.Distribution;
-import io.opencensus.metrics.Point;
-import io.opencensus.metrics.Value;
+import io.opencensus.metrics.export.Distribution;
+import io.opencensus.metrics.export.Point;
+import io.opencensus.metrics.export.Value;
 import io.opencensus.stats.Aggregation;
 import io.opencensus.stats.AggregationData;
 import io.opencensus.stats.AggregationData.DistributionData;
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 80f60ce4..0d25b292 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
@@ -33,11 +33,11 @@ import io.opencensus.common.Timestamp;
 import io.opencensus.implcore.internal.CheckerFrameworkUtils;
 import io.opencensus.implcore.internal.CurrentState.State;
 import io.opencensus.metrics.LabelValue;
-import io.opencensus.metrics.Metric;
-import io.opencensus.metrics.MetricDescriptor;
-import io.opencensus.metrics.MetricDescriptor.Type;
-import io.opencensus.metrics.Point;
-import io.opencensus.metrics.TimeSeries;
+import io.opencensus.metrics.export.Metric;
+import io.opencensus.metrics.export.MetricDescriptor;
+import io.opencensus.metrics.export.MetricDescriptor.Type;
+import io.opencensus.metrics.export.Point;
+import io.opencensus.metrics.export.TimeSeries;
 import io.opencensus.stats.Aggregation;
 import io.opencensus.stats.AggregationData;
 import io.opencensus.stats.Measure;
diff --git a/impl_core/src/main/java/io/opencensus/implcore/stats/StatsComponentImplBase.java b/impl_core/src/main/java/io/opencensus/implcore/stats/StatsComponentImplBase.java
index 72791f04..741b399b 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/stats/StatsComponentImplBase.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/stats/StatsComponentImplBase.java
@@ -21,8 +21,8 @@ import io.opencensus.common.Clock;
 import io.opencensus.implcore.internal.CurrentState;
 import io.opencensus.implcore.internal.CurrentState.State;
 import io.opencensus.implcore.internal.EventQueue;
-import io.opencensus.metrics.MetricProducer;
 import io.opencensus.metrics.Metrics;
+import io.opencensus.metrics.export.MetricProducer;
 import io.opencensus.stats.StatsCollectionState;
 import io.opencensus.stats.StatsComponent;
 
diff --git a/impl_core/src/main/java/io/opencensus/implcore/stats/StatsManager.java b/impl_core/src/main/java/io/opencensus/implcore/stats/StatsManager.java
index a58b9a5e..17e99d46 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/stats/StatsManager.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/stats/StatsManager.java
@@ -22,7 +22,7 @@ import io.opencensus.common.Clock;
 import io.opencensus.implcore.internal.CurrentState;
 import io.opencensus.implcore.internal.CurrentState.State;
 import io.opencensus.implcore.internal.EventQueue;
-import io.opencensus.metrics.Metric;
+import io.opencensus.metrics.export.Metric;
 import io.opencensus.stats.View;
 import io.opencensus.stats.ViewData;
 import io.opencensus.tags.TagContext;
diff --git a/impl_core/src/test/java/io/opencensus/implcore/metrics/GaugeTest.java b/impl_core/src/test/java/io/opencensus/implcore/metrics/GaugeTest.java
index e1c17876..161ad348 100644
--- a/impl_core/src/test/java/io/opencensus/implcore/metrics/GaugeTest.java
+++ b/impl_core/src/test/java/io/opencensus/implcore/metrics/GaugeTest.java
@@ -25,12 +25,12 @@ import io.opencensus.implcore.metrics.Gauge.DoubleGauge;
 import io.opencensus.implcore.metrics.Gauge.LongGauge;
 import io.opencensus.metrics.LabelKey;
 import io.opencensus.metrics.LabelValue;
-import io.opencensus.metrics.Metric;
-import io.opencensus.metrics.MetricDescriptor;
-import io.opencensus.metrics.MetricDescriptor.Type;
-import io.opencensus.metrics.Point;
-import io.opencensus.metrics.TimeSeries;
-import io.opencensus.metrics.Value;
+import io.opencensus.metrics.export.Metric;
+import io.opencensus.metrics.export.MetricDescriptor;
+import io.opencensus.metrics.export.MetricDescriptor.Type;
+import io.opencensus.metrics.export.Point;
+import io.opencensus.metrics.export.TimeSeries;
+import io.opencensus.metrics.export.Value;
 import io.opencensus.testing.common.TestClock;
 import java.util.Collections;
 import java.util.List;
diff --git a/impl_core/src/test/java/io/opencensus/implcore/metrics/MetricRegistryImplTest.java b/impl_core/src/test/java/io/opencensus/implcore/metrics/MetricRegistryImplTest.java
index 0b75a6e0..3a5cb493 100644
--- a/impl_core/src/test/java/io/opencensus/implcore/metrics/MetricRegistryImplTest.java
+++ b/impl_core/src/test/java/io/opencensus/implcore/metrics/MetricRegistryImplTest.java
@@ -23,12 +23,12 @@ import io.opencensus.common.ToDoubleFunction;
 import io.opencensus.common.ToLongFunction;
 import io.opencensus.metrics.LabelKey;
 import io.opencensus.metrics.LabelValue;
-import io.opencensus.metrics.Metric;
-import io.opencensus.metrics.MetricDescriptor;
-import io.opencensus.metrics.MetricDescriptor.Type;
-import io.opencensus.metrics.Point;
-import io.opencensus.metrics.TimeSeries;
-import io.opencensus.metrics.Value;
+import io.opencensus.metrics.export.Metric;
+import io.opencensus.metrics.export.MetricDescriptor;
+import io.opencensus.metrics.export.MetricDescriptor.Type;
+import io.opencensus.metrics.export.Point;
+import io.opencensus.metrics.export.TimeSeries;
+import io.opencensus.metrics.export.Value;
 import io.opencensus.testing.common.TestClock;
 import java.util.Collections;
 import java.util.LinkedHashMap;
diff --git a/impl_core/src/test/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImplTest.java b/impl_core/src/test/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImplTest.java
index 7f2ec153..e549dadb 100644
--- a/impl_core/src/test/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImplTest.java
+++ b/impl_core/src/test/java/io/opencensus/implcore/metrics/export/MetricProducerManagerImplTest.java
@@ -18,7 +18,7 @@ package io.opencensus.implcore.metrics.export;
 
 import static com.google.common.truth.Truth.assertThat;
 
-import io.opencensus.metrics.MetricProducer;
+import io.opencensus.metrics.export.MetricProducer;
 import io.opencensus.metrics.export.MetricProducerManager;
 import java.util.Set;
 import org.junit.Before;
diff --git a/impl_core/src/test/java/io/opencensus/implcore/stats/MetricUtilsTest.java b/impl_core/src/test/java/io/opencensus/implcore/stats/MetricUtilsTest.java
index 7cc8d984..66e971f6 100644
--- a/impl_core/src/test/java/io/opencensus/implcore/stats/MetricUtilsTest.java
+++ b/impl_core/src/test/java/io/opencensus/implcore/stats/MetricUtilsTest.java
@@ -22,8 +22,8 @@ import io.opencensus.common.Duration;
 import io.opencensus.common.Timestamp;
 import io.opencensus.metrics.LabelKey;
 import io.opencensus.metrics.LabelValue;
-import io.opencensus.metrics.MetricDescriptor;
-import io.opencensus.metrics.MetricDescriptor.Type;
+import io.opencensus.metrics.export.MetricDescriptor;
+import io.opencensus.metrics.export.MetricDescriptor.Type;
 import io.opencensus.stats.Aggregation.Count;
 import io.opencensus.stats.Aggregation.Distribution;
 import io.opencensus.stats.Aggregation.LastValue;
diff --git a/impl_core/src/test/java/io/opencensus/implcore/stats/MutableAggregationTest.java b/impl_core/src/test/java/io/opencensus/implcore/stats/MutableAggregationTest.java
index ed85dded..fced533f 100644
--- a/impl_core/src/test/java/io/opencensus/implcore/stats/MutableAggregationTest.java
+++ b/impl_core/src/test/java/io/opencensus/implcore/stats/MutableAggregationTest.java
@@ -28,9 +28,10 @@ import io.opencensus.implcore.stats.MutableAggregation.MutableLastValueLong;
 import io.opencensus.implcore.stats.MutableAggregation.MutableMean;
 import io.opencensus.implcore.stats.MutableAggregation.MutableSumDouble;
 import io.opencensus.implcore.stats.MutableAggregation.MutableSumLong;
-import io.opencensus.metrics.Distribution.Bucket;
-import io.opencensus.metrics.Point;
-import io.opencensus.metrics.Value;
+import io.opencensus.metrics.export.Distribution;
+import io.opencensus.metrics.export.Distribution.Bucket;
+import io.opencensus.metrics.export.Point;
+import io.opencensus.metrics.export.Value;
 import io.opencensus.stats.AggregationData;
 import io.opencensus.stats.AggregationData.CountData;
 import io.opencensus.stats.AggregationData.DistributionData;
@@ -300,7 +301,7 @@ public class MutableAggregationTest {
         .isEqualTo(
             Point.create(
                 Value.distributionValue(
-                    io.opencensus.metrics.Distribution.create(
+                    Distribution.create(
                         0,
                         0,
                         0,