private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.speech.v1p1beta1.SpeechAdaptation.ABNFGrammar,
            com.google.cloud.speech.v1p1beta1.SpeechAdaptation.ABNFGrammar.Builder,
            com.google.cloud.speech.v1p1beta1.SpeechAdaptation.ABNFGrammarOrBuilder>
        getAbnfGrammarFieldBuilder() {
      if (abnfGrammarBuilder_ == null) {
        abnfGrammarBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.speech.v1p1beta1.SpeechAdaptation.ABNFGrammar,
                com.google.cloud.speech.v1p1beta1.SpeechAdaptation.ABNFGrammar.Builder,
                com.google.cloud.speech.v1p1beta1.SpeechAdaptation.ABNFGrammarOrBuilder>(
                getAbnfGrammar(), getParentForChildren(), isClean());
        abnfGrammar_ = null;
      }
      return abnfGrammarBuilder_;
    }
<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