what does checkLanguage do ( android )

[grimace]

I managed to get plugin rebuilt including export for checkLanguage. When I call it, I get no results. I'm calling it like this:

    this.platform.ready().then(() => {
          console.log('calling checkLanguage...');
          tts.checkLanguage().then(function(response) {
            console.log('checkLanguage - success : '+response);
          },function(error) {
            console.log('checkLanguage - error : '+error);
          });
    });

all I ever see in the log is:
calling checkLanguage...
from what I can see ( in the source ) checkLanguage calls:

    tts.getAvailableLanguages();

but I don't see any reference to this anywhere else in the code. Could you explain what should be happening?

Thx