public Builder addAllTimepoints(
        java.lang.Iterable<? extends com.google.cloud.texttospeech.v1beta1.Timepoint> values) {
      if (timepointsBuilder_ == null) {
        ensureTimepointsIsMutable();
        com.google.protobuf.AbstractMessageLite.Builder.addAll(values, timepoints_);
        onChanged();
      } else {
        timepointsBuilder_.addAllMessages(values);
      }
      return this;
    }
<pre>
A link between a position in the original request input and a corresponding
time in the output audio. It's only supported via `&lt;mark&gt;` of SSML input.
</pre>

<code>repeated .google.cloud.texttospeech.v1beta1.Timepoint timepoints = 2;</code>
java-texttospeech/proto-google-cloud-texttospeech-v1beta1/src/main/java/com/google/cloud/texttospeech/v1beta1/SynthesizeSpeechResponse.java