public Builder setAudioConfig(com.google.cloud.texttospeech.v1beta1.AudioConfig value) {
      if (audioConfigBuilder_ == null) {
        if (value == null) {
          throw new NullPointerException();
        }
        audioConfig_ = value;
      } else {
        audioConfigBuilder_.setMessage(value);
      }
      bitField0_ |= 0x00000004;
      onChanged();
      return this;
    }
<pre>
Required. The configuration of the synthesized audio.
</pre>

<code>
.google.cloud.texttospeech.v1beta1.AudioConfig audio_config = 3 [(.google.api.field_behavior) = REQUIRED];
</code>
java-texttospeech/proto-google-cloud-texttospeech-v1beta1/src/main/java/com/google/cloud/texttospeech/v1beta1/SynthesizeLongAudioRequest.java