public com.google.cloud.speech.v2.SpeechRecognitionAlternative.Builder addAlternativesBuilder(
        int index) {
      return getAlternativesFieldBuilder()
          .addBuilder(
              index, com.google.cloud.speech.v2.SpeechRecognitionAlternative.getDefaultInstance());
    }
<pre>
May contain one or more recognition hypotheses. These alternatives are
ordered in terms of accuracy, with the top (first) alternative being the
most probable, as ranked by the recognizer.
</pre>

<code>repeated .google.cloud.speech.v2.SpeechRecognitionAlternative alternatives = 1;</code>
java-speech/proto-google-cloud-speech-v2/src/main/java/com/google/cloud/speech/v2/SpeechRecognitionResult.java