public Builder clearMarkup() {
      if (inputSourceCase_ == 5) {
        inputSourceCase_ = 0;
        inputSource_ = null;
        onChanged();
      }
      return this;
    }
<pre>
Markup for HD voices specifically. This field may not be used with any
other voices.
</pre>

<code>string markup = 5;</code>

@return This builder for chaining.
java-texttospeech/proto-google-cloud-texttospeech-v1/src/main/java/com/google/cloud/texttospeech/v1/StreamingSynthesisInput.java