private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.vertexai.api.RetrievalMetadata,
            com.google.cloud.vertexai.api.RetrievalMetadata.Builder,
            com.google.cloud.vertexai.api.RetrievalMetadataOrBuilder>
        getRetrievalMetadataFieldBuilder() {
      if (retrievalMetadataBuilder_ == null) {
        retrievalMetadataBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.vertexai.api.RetrievalMetadata,
                com.google.cloud.vertexai.api.RetrievalMetadata.Builder,
                com.google.cloud.vertexai.api.RetrievalMetadataOrBuilder>(
                getRetrievalMetadata(), getParentForChildren(), isClean());
        retrievalMetadata_ = null;
      }
      return retrievalMetadataBuilder_;
    }
<pre>
Optional. Output only. Retrieval metadata.
</pre>

<code>
optional .google.cloud.vertexai.v1.RetrievalMetadata retrieval_metadata = 7 [(.google.api.field_behavior) = OPTIONAL, (.google.api.field_behavior) = OUTPUT_ONLY];
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/GroundingMetadata.java