I started getting that error today when trying to make a set of resolvers more generic. I.e., a public abstract class FooQueryResolver<T extends Foo> implements GraphQLResolver<T> { public String getValue (T foo) { return foo.getValue();} } and then other resolvers for the child classes like BarResolver extends FooResolver<Bar> (where Bar is a child class of Foo)

I've tried playing around making the actual Foo example with two simple subclasses and it seems to work so I'm guessing it is how I have my actual real resolvers setup, but my real example is more complicated so maybe it is a bug.

Any thoughts on how to work out if this is a graphql-java-tools bug or an error with how I have my resolvers set up?