@java.lang.Override
    public java.lang.String getSpeaker() {
      java.lang.Object ref = speaker_;
      if (ref instanceof java.lang.String) {
        return (java.lang.String) ref;
      } else {
        com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
        java.lang.String s = bs.toStringUtf8();
        speaker_ = s;
        return s;
      }
    }
<pre>
Required. The speaker of the turn, for example, 'O' or 'Q'. Please refer
to documentation for available speakers.
</pre>

<code>string speaker = 1 [(.google.api.field_behavior) = REQUIRED];</code>

@return The speaker.
java-texttospeech/proto-google-cloud-texttospeech-v1/src/main/java/com/google/cloud/texttospeech/v1/MultiSpeakerMarkup.java