Using parameters with javabean collection

I love the fact that jasper can work with javabeans, as it allows me to write any java code i want and be able to get the result, and do it incredibly easily. But the problem is i dont see a way to send custom input from jasper to my collection provider. If i could just get that i could do anything.

Also the reason why we want to do this is so that we can get psuedo spark support.