public Builder setAlternativeLanguageCodes(int index, java.lang.String value) {
      if (value == null) {
        throw new NullPointerException();
      }
      ensureAlternativeLanguageCodesIsMutable();
      alternativeLanguageCodes_.set(index, value);
      bitField0_ |= 0x00000020;
      onChanged();
      return this;
    }
<pre>
A list of up to 3 additional
[BCP-47](https://www.rfc-editor.org/rfc/bcp/bcp47.txt) language tags,
listing possible alternative languages of the supplied audio.
See [Language
Support](https://cloud.google.com/speech-to-text/docs/languages) for a list
of the currently supported language codes. If alternative languages are
listed, recognition result will contain recognition in the most likely
language detected including the main language_code. The recognition result
will include the language tag of the language detected in the audio. Note:
This feature is only supported for Voice Command and Voice Search use cases
and performance may vary for other use cases (e.g., phone call
transcription).
</pre>

<code>repeated string alternative_language_codes = 18;</code>

@param index The index to set the value at.
@param value The alternativeLanguageCodes to set.
@return This builder for chaining.
java-speech/proto-google-cloud-speech-v1/src/main/java/com/google/cloud/speech/v1/RecognitionConfig.java