Accumulate with nested field binding has bad type inference

(I'm completely new to Drools, so bear with me as I try to describe this)

When a rule specifies an accumulate CE containing a variable bound to a nested field expression, the inferred type of the variable is incorrect. I have attached a pull request containing a unit test that is broken by this bug. If I make the nested class' field private and add a getter for it, the test passes.