public Builder clearVttCaptions() {
      vttCaptions_ = getDefaultInstance().getVttCaptions();
      bitField0_ = (bitField0_ & ~0x00000002);
      onChanged();
      return this;
    }
<pre>
The transcript for the audio file as VTT formatted captions. This is
populated only when `VTT` output is requested.
</pre>

<code>string vtt_captions = 2;</code>

@return This builder for chaining.
java-speech/proto-google-cloud-speech-v2/src/main/java/com/google/cloud/speech/v2/InlineResult.java