public static String getDefaultMtlsEndpoint() {
    return "texttospeech.mtls.googleapis.com:443";
  }
Returns the default mTLS service endpoint.
java-texttospeech/google-cloud-texttospeech/src/main/java/com/google/cloud/texttospeech/v1beta1/stub/TextToSpeechStubSettings.java