Codegen for events

Writing events is currently very verbose, requiring lots of boilerplate code.

Additionally, many events simply take the form

for (Callback callback : callbacks) {
    callback.onEvent(...);
}

See also this comment in EventFactory

[LemmaEOF]

I think whatever form this takes should be optional - there are scenarios where you’d want something more complex than a forEach, like early-exit.

[liach]

An alternative I think of would be a factory method to generate Function<T[], T>, possibly when given Class<T> and/or the method to dispatch, either as a Method or a MethodHandle. However, it is still restricted, since not all callbacks just call sub-callbacks; some have early halt or tristate merging, so the usefulness isn’t as much as we would assume.

In addition, we need to check the performance of that Function to make sure it’s not slower than the current lambda meta call site. Somewhere it says Proxy makes spring calls about 10% to 20% slower than direct interface calls.