@java.lang.Override
  public Builder toBuilder() {
    return this == DEFAULT_INSTANCE ? new Builder() : new Builder().mergeFrom(this);
  }
<pre>
Augmented Backus-Naur form (ABNF) is a standardized grammar notation
comprised by a set of derivation rules.
See specifications: https://www.w3.org/TR/speech-grammar
</pre>

<code>.google.cloud.speech.v1p1beta1.SpeechAdaptation.ABNFGrammar abnf_grammar = 4;</code>
java-speech/proto-google-cloud-speech-v1p1beta1/src/main/java/com/google/cloud/speech/v1p1beta1/SpeechAdaptation.java