public com.google.protobuf.ByteString getEventIdBytes() {
      java.lang.Object ref = eventId_;
      if (ref instanceof String) {
        com.google.protobuf.ByteString b =
            com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);
        eventId_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
<pre>
User defined Event Id, used to classify event, within a delivery interval,
events from the same application instance with the same id will be
de-duplicated &amp; only first one will be sent out. Empty event_id will be
treated as "".
</pre>

<code>string event_id = 3;</code>

@return The bytes for eventId.
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/AppPlatformEventBody.java