public Builder mergeAbnfGrammar(
        com.google.cloud.speech.v1p1beta1.SpeechAdaptation.ABNFGrammar value) {
      if (abnfGrammarBuilder_ == null) {
        if (((bitField0_ & 0x00000008) != 0)
            && abnfGrammar_ != null
            && abnfGrammar_
                != com.google.cloud.speech.v1p1beta1.SpeechAdaptation.ABNFGrammar
                    .getDefaultInstance()) {
          getAbnfGrammarBuilder().mergeFrom(value);
        } else {
          abnfGrammar_ = value;
        }
      } else {
        abnfGrammarBuilder_.mergeFrom(value);
      }
      if (abnfGrammar_ != null) {
        bitField0_ |= 0x00000008;
        onChanged();
      }
      return 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