format.

Author: rmehta19

gax-java/gax-grpc/src/main/java/com/google/api/gax/grpc/InstantiatingGrpcChannelProvider.java

@@ -178,6 +178,12 @@ static void resetS2AChannelCredentials() {
     }
   }
 
+  /**
+   * Returns the s2aChannelCredentials of the {@link InstantiatingGrpcChannelProvider} class for
+   * testing purposes.
+   *
+   * <p>This should only be called from tests.
+   */
   @VisibleForTesting
   static ChannelCredentials getS2AChannelCredentials() {
     return s2aChannelCredentials;