@java.lang.Override
  public com.google.cloud.texttospeech.v1beta1.SynthesisInput getInput() {
    return input_ == null
        ? com.google.cloud.texttospeech.v1beta1.SynthesisInput.getDefaultInstance()
        : input_;
  }
<pre>
Required. The Synthesizer requires either plain text or SSML as input.
</pre>

<code>
.google.cloud.texttospeech.v1beta1.SynthesisInput input = 2 [(.google.api.field_behavior) = REQUIRED];
</code>

@return The input.
java-texttospeech/proto-google-cloud-texttospeech-v1beta1/src/main/java/com/google/cloud/texttospeech/v1beta1/SynthesizeLongAudioRequest.java