public boolean hasHeartbeat() {
      return controlCase_ == 1;
    }
<pre>
A server heartbeat.
</pre>

<code>bool heartbeat = 1;</code>

@return Whether the heartbeat field is set.
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/ReceiveEventsControlResponse.java