public Builder setTurns(
        int index, com.google.cloud.texttospeech.v1.MultiSpeakerMarkup.Turn value) {
      if (turnsBuilder_ == null) {
        if (value == null) {
          throw new NullPointerException();
        }
        ensureTurnsIsMutable();
        turns_.set(index, value);
        onChanged();
      } else {
        turnsBuilder_.setMessage(index, value);
      }
      return this;
    }
<pre>
Required. Speaker turns.
</pre>

<code>
repeated .google.cloud.texttospeech.v1.MultiSpeakerMarkup.Turn turns = 1 [(.google.api.field_behavior) = REQUIRED];
</code>
java-texttospeech/proto-google-cloud-texttospeech-v1/src/main/java/com/google/cloud/texttospeech/v1/MultiSpeakerMarkup.java