public Builder mergeCitationMetadata(com.google.cloud.vertexai.api.CitationMetadata value) {
      if (citationMetadataBuilder_ == null) {
        if (((bitField0_ & 0x00000100) != 0)
            && citationMetadata_ != null
            && citationMetadata_
                != com.google.cloud.vertexai.api.CitationMetadata.getDefaultInstance()) {
          getCitationMetadataBuilder().mergeFrom(value);
        } else {
          citationMetadata_ = value;
        }
      } else {
        citationMetadataBuilder_.mergeFrom(value);
      }
      if (citationMetadata_ != null) {
        bitField0_ |= 0x00000100;
        onChanged();
      }
      return this;
    }
<pre>
Output only. Source attribution of the generated content.
</pre>

<code>
.google.cloud.vertexai.v1.CitationMetadata citation_metadata = 6 [(.google.api.field_behavior) = OUTPUT_ONLY];
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/Candidate.java