code: @Override
      public AddTagsToResourceResult addTagsToResource(AddTagsToResourceRequest request) {
          request = beforeClientExecution(request);
          return executeAddTagsToResource(request);
      }
docs: <p>
  Adds metadata tags to an Amazon Neptune resource. These tags can also be used with cost allocation reporting to
  track cost associated with Amazon Neptune resources, or used in a Condition statement in an IAM policy for Amazon
  Neptune.
  </p>
  
  @param addTagsToResourceRequest
  @return Result of the AddTagsToResource operation returned by the service.
  @throws DBInstanceNotFoundException
  <i>DBInstanceIdentifier</i> does not refer to an existing DB instance.
  @throws DBSnapshotNotFoundException
  <i>DBSnapshotIdentifier</i> does not refer to an existing DB snapshot.
  @throws DBClusterNotFoundException
  <i>DBClusterIdentifier</i> does not refer to an existing DB cluster.
  @sample AmazonNeptune.AddTagsToResource
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/neptune-2014-10-31/AddTagsToResource" target="_top">AWS API
  Documentation</a>