public com.google.protobuf.DurationOrBuilder getTotalBilledDurationOrBuilder() {
      if (totalBilledDurationBuilder_ != null) {
        return totalBilledDurationBuilder_.getMessageOrBuilder();
      } else {
        return totalBilledDuration_ == null
            ? com.google.protobuf.Duration.getDefaultInstance()
            : totalBilledDuration_;
      }
    }
<pre>
When available, billed audio seconds for the corresponding request.
</pre>

<code>.google.protobuf.Duration total_billed_duration = 6;</code>
java-speech/proto-google-cloud-speech-v2/src/main/java/com/google/cloud/speech/v2/RecognitionResponseMetadata.java