@java.lang.Override
  public int getSerializedSize() {
    int size = memoizedSize;
    if (size != -1) return size;

    size = 0;
    if (streamingRequestCase_ == 1) {
      size +=
          com.google.protobuf.CodedOutputStream.computeMessageSize(
              1,
              (com.google.cloud.texttospeech.v1beta1.StreamingSynthesizeConfig) streamingRequest_);
    }
    if (streamingRequestCase_ == 2) {
      size +=
          com.google.protobuf.CodedOutputStream.computeMessageSize(
              2, (com.google.cloud.texttospeech.v1beta1.StreamingSynthesisInput) streamingRequest_);
    }
    size += getUnknownFields().getSerializedSize();
    memoizedSize = size;
    return size;
  }
<pre>
Input to synthesize. Specified in all messages but the first in a
`StreamingSynthesize` call.
</pre>

<code>.google.cloud.texttospeech.v1beta1.StreamingSynthesisInput input = 2;</code>
java-texttospeech/proto-google-cloud-texttospeech-v1beta1/src/main/java/com/google/cloud/texttospeech/v1beta1/StreamingSynthesizeRequest.java