public final ListVoicesResponse listVoices(String languageCode) {
    ListVoicesRequest request =
        ListVoicesRequest.newBuilder().setLanguageCode(languageCode).build();
    return listVoices(request);
  }
Returns a list of Voice supported for synthesis.

<p>Sample code:

<pre>{@code
// This snippet has been automatically generated and should be regarded as a code template only.
// It will require modifications to work:
// - It may require correct/in-range values for request initialization.
// - It may require specifying regional endpoints when creating the service client as shown in
// https://cloud.google.com/java/docs/setup#configure_endpoints_for_the_client_library
try (TextToSpeechClient textToSpeechClient = TextToSpeechClient.create()) {
  String languageCode = "languageCode-2092349083";
  ListVoicesResponse response = textToSpeechClient.listVoices(languageCode);
}
}</pre>

@param languageCode Optional. Recommended.
    [BCP-47](https://www.rfc-editor.org/rfc/bcp/bcp47.txt) language tag. If not specified, the
    API will return all supported voices. If specified, the ListVoices call will only return
    voices that can be used to synthesize this language_code. For example, if you specify
    `"en-NZ"`, all `"en-NZ"` voices will be returned. If you specify `"no"`, both
    `"no-\\&#42;"` (Norwegian) and `"nb-\\&#42;"` (Norwegian Bokmal) voices will be returned.
@throws com.google.api.gax.rpc.ApiException if the remote call fails
java-texttospeech/google-cloud-texttospeech/src/main/java/com/google/cloud/texttospeech/v1beta1/TextToSpeechClient.java