private com.google.protobuf.MapField<
          java.lang.String, com.google.cloud.visionai.v1.AnnotationValue>
      internalGetElements() {
    if (elements_ == null) {
      return com.google.protobuf.MapField.emptyMapField(ElementsDefaultEntryHolder.defaultEntry);
    }
    return elements_;
  }
<pre>
Customized struct represnation in annotation.
</pre>

Protobuf type {@code google.cloud.visionai.v1.AnnotationCustomizedStruct}
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/AnnotationCustomizedStruct.java