Recognize only phrases - not individual words

I am using the Android demo and I am trying to have vosk only recognize entire phrases (mostly to improve accuracy and speed). I set the "phrase" parameter of Recognizer() to
["how are you","i am fine","[unk]"]
When I say "how fine" vosk recognizes that. I would expect it to return [unk].

Am I doing something wrong here or is this a bug?

Aside from adding a wakeup command to each phrase, is there another method to achieve that?