public final OperationFuture<SynthesizeLongAudioResponse, SynthesizeLongAudioMetadata>
      synthesizeLongAudioAsync(SynthesizeLongAudioRequest request) {
    return synthesizeLongAudioOperationCallable().futureCall(request);
  }
Synthesizes long form text asynchronously.

<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 (TextToSpeechLongAudioSynthesizeClient textToSpeechLongAudioSynthesizeClient =
    TextToSpeechLongAudioSynthesizeClient.create()) {
  SynthesizeLongAudioRequest request =
      SynthesizeLongAudioRequest.newBuilder()
          .setParent("parent-995424086")
          .setInput(SynthesisInput.newBuilder().build())
          .setAudioConfig(AudioConfig.newBuilder().build())
          .setOutputGcsUri("outputGcsUri-489598154")
          .setVoice(VoiceSelectionParams.newBuilder().build())
          .build();
  SynthesizeLongAudioResponse response =
      textToSpeechLongAudioSynthesizeClient.synthesizeLongAudioAsync(request).get();
}
}</pre>

@param request The request object containing all of the parameters for the API call.
@throws com.google.api.gax.rpc.ApiException if the remote call fails
java-texttospeech/google-cloud-texttospeech/src/main/java/com/google/cloud/texttospeech/v1/TextToSpeechLongAudioSynthesizeClient.java