@java.lang.Override
    public int hashCode() {
      if (memoizedHashCode != 0) {
        return memoizedHashCode;
      }
      int hash = 41;
      hash = (19 * hash) + getDescriptor().hashCode();
      hash = (37 * hash) + ID_FIELD_NUMBER;
      hash = (53 * hash) + getId().hashCode();
      hash = (37 * hash) + DISPLAY_NAME_FIELD_NUMBER;
      hash = (53 * hash) + getDisplayName().hashCode();
      if (hasBoundingBox()) {
        hash = (37 * hash) + BOUNDING_BOX_FIELD_NUMBER;
        hash = (53 * hash) + getBoundingBox().hashCode();
      }
      hash = (37 * hash) + CONFIDENCE_FIELD_NUMBER;
      hash = (53 * hash) + java.lang.Float.floatToIntBits(getConfidence());
      hash = (37 * hash) + TRACK_ID_FIELD_NUMBER;
      hash = (53 * hash) + com.google.protobuf.Internal.hashLong(getTrackId());
      hash = (29 * hash) + getUnknownFields().hashCode();
      memoizedHashCode = hash;
      return hash;
    }
<pre>
The same object may be identified on muitiple frames which are typical
adjacent. The set of frames where a particular object has been detected
form a track. This track_id can be used to trace down all frames for an
detected object.
</pre>

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

@return The trackId.
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/VideoObjectTrackingPredictionResult.java