@java.lang.Override
  public java.lang.String getLanguageCode() {
    java.lang.Object ref = languageCode_;
    if (ref instanceof java.lang.String) {
      return (java.lang.String) ref;
    } else {
      com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
      java.lang.String s = bs.toStringUtf8();
      languageCode_ = s;
      return s;
    }
  }
<pre>
Required. The language (and potentially also the region) of the voice
expressed as a [BCP-47](https://www.rfc-editor.org/rfc/bcp/bcp47.txt)
language tag, e.g. "en-US". This should not include a script tag (e.g. use
"cmn-cn" rather than "cmn-Hant-cn"), because the script will be inferred
from the input provided in the SynthesisInput.  The TTS service
will use this parameter to help choose an appropriate voice.  Note that
the TTS service may choose a voice with a slightly different language code
than the one selected; it may substitute a different region
(e.g. using en-US rather than en-CA if there isn't a Canadian voice
available), or even a different language, e.g. using "nb" (Norwegian
Bokmal) instead of "no" (Norwegian)".
</pre>

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

@return The languageCode.
java-texttospeech/proto-google-cloud-texttospeech-v1/src/main/java/com/google/cloud/texttospeech/v1/VoiceSelectionParams.java