public com.google.protobuf.ByteString getDisplayLanguageCodeBytes() {
      java.lang.Object ref = displayLanguageCode_;
      if (ref instanceof String) {
        com.google.protobuf.ByteString b =
            com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);
        displayLanguageCode_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
<pre>
Optional. The language to use to return localized, human readable names
of supported languages. If missing, then display names are not returned
in a response.
</pre>

<code>string display_language_code = 1 [(.google.api.field_behavior) = OPTIONAL];</code>

@return The bytes for displayLanguageCode.
java-translate/proto-google-cloud-translate-v3beta1/src/main/java/com/google/cloud/translate/v3beta1/GetSupportedLanguagesRequest.java