@java.lang.Override
    public int getSerializedSize() {
      int size = memoizedSize;
      if (size != -1) return size;

      size = 0;
      if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(id_)) {
        size += com.google.protobuf.GeneratedMessageV3.computeStringSize(1, id_);
      }
      if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(displayName_)) {
        size += com.google.protobuf.GeneratedMessageV3.computeStringSize(2, displayName_);
      }
      if (((bitField0_ & 0x00000001) != 0)) {
        size += com.google.protobuf.CodedOutputStream.computeMessageSize(3, getBoundingBox());
      }
      if (java.lang.Float.floatToRawIntBits(confidence_) != 0) {
        size += com.google.protobuf.CodedOutputStream.computeFloatSize(4, confidence_);
      }
      if (trackId_ != 0L) {
        size += com.google.protobuf.CodedOutputStream.computeInt64Size(5, trackId_);
      }
      size += getUnknownFields().getSerializedSize();
      memoizedSize = size;
      return size;
    }
<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