public java.lang.String getDisplayLanguageCode() {
      java.lang.Object ref = displayLanguageCode_;
      if (!(ref instanceof java.lang.String)) {
        com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
        java.lang.String s = bs.toStringUtf8();
        displayLanguageCode_ = s;
        return s;
      } else {
        return (java.lang.String) 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 displayLanguageCode.
java-translate/proto-google-cloud-translate-v3/src/main/java/com/google/cloud/translate/v3/GetSupportedLanguagesRequest.java