public Builder clearTrackId() {
        trackId_ = getDefaultInstance().getTrackId();
        bitField0_ = (bitField0_ & ~0x00000001);
        onChanged();
        return this;
      }
<pre>
An unique id to identify a track. It should be consistent across frames.
</pre>

<code>string track_id = 1;</code>

@return This builder for chaining.
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/OccupancyCountingPredictionResult.java