cast method
Implementation
InputAudioConfig cast(){
InputAudioConfig c = InputAudioConfig();
c.languageCode = this.languageCode;
c.sampleRateHertz = this.sampleRateHertz;
c.singleUtterance = this.singleUtterance;
c.audioEncoding = getAudioEncoding(this.encoding);
c.speechContexts.addAll(speechContexts.map((sc) => sc.toGoogleSpeechContext()));
return c;
}