how to use jar libraries to call java functions in c#?(is it possible at all?)

hi.
i want to make in app purchase for my game. as shop platform i want to work with just has given a java api to work and soomla version doesnt work very well with 5 version of unity. i know that its possible to call java functions in c# but as its script and unity uses xamarin maybe i think there is compiler difficulities to handle.

i want to know can i really do that or not.
thank you for helping.

You will probably have better luck in the Android platform subforum than here.