public Builder addTracks(int index, com.google.cloud.videointelligence.v1.Track value) {
      if (tracksBuilder_ == null) {
        if (value == null) {
          throw new NullPointerException();
        }
        ensureTracksIsMutable();
        tracks_.add(index, value);
        onChanged();
      } else {
        tracksBuilder_.addMessage(index, value);
      }
      return this;
    }
<pre>
The detected tracks of a person.
</pre>

<code>repeated .google.cloud.videointelligence.v1.Track tracks = 1;</code>
java-video-intelligence/proto-google-cloud-video-intelligence-v1/src/main/java/com/google/cloud/videointelligence/v1/PersonDetectionAnnotation.java