private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.visionai.v1.NormalizedPolygon,
            com.google.cloud.visionai.v1.NormalizedPolygon.Builder,
            com.google.cloud.visionai.v1.NormalizedPolygonOrBuilder>
        getActiveZoneFieldBuilder() {
      if (activeZoneBuilder_ == null) {
        if (!(annotationPayloadCase_ == 5)) {
          annotationPayload_ = com.google.cloud.visionai.v1.NormalizedPolygon.getDefaultInstance();
        }
        activeZoneBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.visionai.v1.NormalizedPolygon,
                com.google.cloud.visionai.v1.NormalizedPolygon.Builder,
                com.google.cloud.visionai.v1.NormalizedPolygonOrBuilder>(
                (com.google.cloud.visionai.v1.NormalizedPolygon) annotationPayload_,
                getParentForChildren(),
                isClean());
        annotationPayload_ = null;
      }
      annotationPayloadCase_ = 5;
      onChanged();
      return activeZoneBuilder_;
    }
<pre>
Annotation for type ACTIVE_ZONE
</pre>

<code>.google.cloud.visionai.v1.NormalizedPolygon active_zone = 5;</code>
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/StreamAnnotation.java