private void ensureAttributesIsMutable() {
      if (!((bitField0_ & 0x00000004) != 0)) {
        attributes_ =
            new java.util.ArrayList<com.google.cloud.videointelligence.v1.DetectedAttribute>(
                attributes_);
        bitField0_ |= 0x00000004;
      }
    }
<pre>
Time-offset, relative to the beginning of the video,
corresponding to the video frame for this object.
</pre>

<code>.google.protobuf.Duration time_offset = 2;</code>
java-video-intelligence/proto-google-cloud-video-intelligence-v1/src/main/java/com/google/cloud/videointelligence/v1/TimestampedObject.java