public Builder clearZoneId() {
        zoneId_ = getDefaultInstance().getZoneId();
        bitField0_ = (bitField0_ & ~0x00000002);
        onChanged();
        return this;
      }
<pre>
The unique id for the zone in which the object is dwelling/waiting.
</pre>

<code>string zone_id = 2;</code>

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