Audio format OGG_OPUS is not yet supported

Since many openhub versions I get this warning for "Google Cloud Text-to-Speech"

  • Level

    WARN

  • Logger Class

    org.openhab.voice.googletts.internal.GoogleTTSService

  • Message

    Audio format OGG_OPUS is not yet supported.

According to googleAI I should change to mp3 - but I am not able to find where.

Thank for any help. Running Openhabian 5.2