Fix incorrect argument to Checker Framework, and fix nullness warnings. (#1354)

709d97aa321d5729988fd63b960bbece04cfba10 modified the -AskipDefs argument to the
Checker Framework (a regular expression) in a way that caused it to skip
checking all files.  This commit fixes the regular expression and the new
Checker Framework warnings.

3 files changed, 9 insertions, 7 deletions

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 a7fa0da4..ddfce618 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
@@ -348,9 +348,10 @@ abstract class MutableAggregation {
         this.bucketCounts[i] += bucketCounts[i];
       }
 
-      if (exemplars != null) {
-        for (int i = 0; i < mutableDistribution.getExemplars().length; i++) {
-          Exemplar exemplar = mutableDistribution.getExemplars()[i];
+      Exemplar[] otherExemplars = mutableDistribution.getExemplars();
+      if (exemplars != null && otherExemplars != null) {
+        for (int i = 0; i < otherExemplars.length; i++) {
+          Exemplar exemplar = otherExemplars[i];
           // Assume other is always newer than this, because we combined interval buckets in time
           // order.
           // If there's a newer exemplar, overwrite current value.
diff --git a/impl_core/src/main/java/io/opencensus/implcore/stats/RecordUtils.java b/impl_core/src/main/java/io/opencensus/implcore/stats/RecordUtils.java
index 5dc77cb1..200a054b 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/stats/RecordUtils.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/stats/RecordUtils.java
@@ -143,7 +143,7 @@ final class RecordUtils {
     return measurement.match(
         GET_VALUE_FROM_MEASUREMENT_DOUBLE,
         GET_VALUE_FROM_MEASUREMENT_LONG,
-        Functions.</*@Nullable*/ Double>throwAssertionError());
+        Functions.<Double>throwAssertionError());
   }
 
   // static inner Function classes
@@ -263,8 +263,9 @@ final class RecordUtils {
         boxedBucketCounts.add(bucketCount);
       }
       List<Exemplar> exemplars = new ArrayList<Exemplar>();
-      if (arg.getExemplars() != null) {
-        for (Exemplar exemplar : arg.getExemplars()) {
+      Exemplar[] exemplarArray = arg.getExemplars();
+      if (exemplarArray != null) {
+        for (Exemplar exemplar : exemplarArray) {
           if (exemplar != null) {
             exemplars.add(exemplar);
           }
diff --git a/impl_core/src/main/java/io/opencensus/implcore/trace/SpanBuilderImpl.java b/impl_core/src/main/java/io/opencensus/implcore/trace/SpanBuilderImpl.java
index f5d74393..3c5f20c6 100644
--- a/impl_core/src/main/java/io/opencensus/implcore/trace/SpanBuilderImpl.java
+++ b/impl_core/src/main/java/io/opencensus/implcore/trace/SpanBuilderImpl.java
@@ -241,7 +241,7 @@ final class SpanBuilderImpl extends SpanBuilder {
   }
 
   @Override
-  public SpanBuilderImpl setSpanKind(Kind kind) {
+  public SpanBuilderImpl setSpanKind(@Nullable Kind kind) {
     this.kind = kind;
     return this;
   }