private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.translate.v3.AdaptiveMtTranslateRequest.ReferenceSentenceConfig,
            com.google.cloud.translate.v3.AdaptiveMtTranslateRequest.ReferenceSentenceConfig
                .Builder,
            com.google.cloud.translate.v3.AdaptiveMtTranslateRequest
                .ReferenceSentenceConfigOrBuilder>
        getReferenceSentenceConfigFieldBuilder() {
      if (referenceSentenceConfigBuilder_ == null) {
        referenceSentenceConfigBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.translate.v3.AdaptiveMtTranslateRequest.ReferenceSentenceConfig,
                com.google.cloud.translate.v3.AdaptiveMtTranslateRequest.ReferenceSentenceConfig
                    .Builder,
                com.google.cloud.translate.v3.AdaptiveMtTranslateRequest
                    .ReferenceSentenceConfigOrBuilder>(
                getReferenceSentenceConfig(), getParentForChildren(), isClean());
        referenceSentenceConfig_ = null;
      }
      return referenceSentenceConfigBuilder_;
    }
<pre>
Configuration for caller provided reference sentences.
</pre>

<code>
optional .google.cloud.translation.v3.AdaptiveMtTranslateRequest.ReferenceSentenceConfig reference_sentence_config = 6;
</code>
java-translate/proto-google-cloud-translate-v3/src/main/java/com/google/cloud/translate/v3/AdaptiveMtTranslateRequest.java