private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.vertexai.api.RagRetrievalConfig,
            com.google.cloud.vertexai.api.RagRetrievalConfig.Builder,
            com.google.cloud.vertexai.api.RagRetrievalConfigOrBuilder>
        getRagRetrievalConfigFieldBuilder() {
      if (ragRetrievalConfigBuilder_ == null) {
        ragRetrievalConfigBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.vertexai.api.RagRetrievalConfig,
                com.google.cloud.vertexai.api.RagRetrievalConfig.Builder,
                com.google.cloud.vertexai.api.RagRetrievalConfigOrBuilder>(
                getRagRetrievalConfig(), getParentForChildren(), isClean());
        ragRetrievalConfig_ = null;
      }
      return ragRetrievalConfigBuilder_;
    }
<pre>
Optional. The retrieval config for the Rag query.
</pre>

<code>
.google.cloud.vertexai.v1.RagRetrievalConfig rag_retrieval_config = 6 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/VertexRagStore.java