private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.texttospeech.v1.StreamingSynthesisInput,
            com.google.cloud.texttospeech.v1.StreamingSynthesisInput.Builder,
            com.google.cloud.texttospeech.v1.StreamingSynthesisInputOrBuilder>
        getInputFieldBuilder() {
      if (inputBuilder_ == null) {
        if (!(streamingRequestCase_ == 2)) {
          streamingRequest_ =
              com.google.cloud.texttospeech.v1.StreamingSynthesisInput.getDefaultInstance();
        }
        inputBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.texttospeech.v1.StreamingSynthesisInput,
                com.google.cloud.texttospeech.v1.StreamingSynthesisInput.Builder,
                com.google.cloud.texttospeech.v1.StreamingSynthesisInputOrBuilder>(
                (com.google.cloud.texttospeech.v1.StreamingSynthesisInput) streamingRequest_,
                getParentForChildren(),
                isClean());
        streamingRequest_ = null;
      }
      streamingRequestCase_ = 2;
      onChanged();
      return inputBuilder_;
    }
<pre>
Input to synthesize. Specified in all messages but the first in a
`StreamingSynthesize` call.
</pre>

<code>.google.cloud.texttospeech.v1.StreamingSynthesisInput input = 2;</code>
java-texttospeech/proto-google-cloud-texttospeech-v1/src/main/java/com/google/cloud/texttospeech/v1/StreamingSynthesizeRequest.java