public Builder clearTurns() {
      if (turnsBuilder_ == null) {
        turns_ = java.util.Collections.emptyList();
        bitField0_ = (bitField0_ & ~0x00000001);
        onChanged();
      } else {
        turnsBuilder_.clear();
      }
      return this;
    }
<pre>
Required. Speaker turns.
</pre>

<code>
repeated .google.cloud.texttospeech.v1beta1.MultiSpeakerMarkup.Turn turns = 1 [(.google.api.field_behavior) = REQUIRED];
</code>
java-texttospeech/proto-google-cloud-texttospeech-v1beta1/src/main/java/com/google/cloud/texttospeech/v1beta1/MultiSpeakerMarkup.java