Merge branch 'master' into pr-merge-386-377-356

pom.xml

@@ -157,10 +157,9 @@
     <google.iam.version>1.0.10</google.iam.version>
     <google.auth.version>0.24.0</google.auth.version>
     <google.api.version>1.31.2</google.api.version>
-    <google.http.version>1.38.1</google.http.version>
     <google.http.version>1.39.0</google.http.version>
     <grpc.version>1.36.0</grpc.version>
-    <protobuf.version>3.15.2</protobuf.version>
+    <protobuf.version>3.15.3</protobuf.version>
     <opencensus.version>0.28.0</opencensus.version>
     <annotations-api.version>1.3.2</annotations-api.version>
     <guava.version>30.1-android</guava.version><!-- We are currently using the *-android version to support JDK7. -->