@java.lang.Override
  public long getTrackId() {
    if (trackInfoCase_ == 5) {
      return (java.lang.Long) trackInfo_;
    }
    return 0L;
  }
<pre>
Streaming mode ONLY.
In streaming mode, we do not know the end time of a tracked object
before it is completed. Hence, there is no VideoSegment info returned.
Instead, we provide a unique identifiable integer track_id so that
the customers can correlate the results of the ongoing
ObjectTrackAnnotation of the same track_id over time.
</pre>

<code>int64 track_id = 5;</code>

@return The trackId.
java-video-intelligence/proto-google-cloud-video-intelligence-v1p3beta1/src/main/java/com/google/cloud/videointelligence/v1p3beta1/ObjectTrackingAnnotation.java