private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.vertexai.api.GroundingMetadata,
            com.google.cloud.vertexai.api.GroundingMetadata.Builder,
            com.google.cloud.vertexai.api.GroundingMetadataOrBuilder>
        getGroundingMetadataFieldBuilder() {
      if (groundingMetadataBuilder_ == null) {
        groundingMetadataBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.vertexai.api.GroundingMetadata,
                com.google.cloud.vertexai.api.GroundingMetadata.Builder,
                com.google.cloud.vertexai.api.GroundingMetadataOrBuilder>(
                getGroundingMetadata(), getParentForChildren(), isClean());
        groundingMetadata_ = null;
      }
      return groundingMetadataBuilder_;
    }
<pre>
Output only. Metadata specifies sources used to ground generated content.
</pre>

<code>
.google.cloud.vertexai.v1.GroundingMetadata grounding_metadata = 7 [(.google.api.field_behavior) = OUTPUT_ONLY];
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/Candidate.java