@java.lang.Override
    public com.google.cloud.texttospeech.v1.MultiSpeakerMarkupOrBuilder
        getMultiSpeakerMarkupOrBuilder() {
      if ((inputSourceCase_ == 4) && (multiSpeakerMarkupBuilder_ != null)) {
        return multiSpeakerMarkupBuilder_.getMessageOrBuilder();
      } else {
        if (inputSourceCase_ == 4) {
          return (com.google.cloud.texttospeech.v1.MultiSpeakerMarkup) inputSource_;
        }
        return com.google.cloud.texttospeech.v1.MultiSpeakerMarkup.getDefaultInstance();
      }
    }
<pre>
The multi-speaker input to be synthesized. Only applicable for
multi-speaker synthesis.
</pre>

<code>.google.cloud.texttospeech.v1.MultiSpeakerMarkup multi_speaker_markup = 4;</code>
java-texttospeech/proto-google-cloud-texttospeech-v1/src/main/java/com/google/cloud/texttospeech/v1/SynthesisInput.java