As the javac's backend is transforming and simplifying code, it often needs to create new AST nodes. However, that is fairly complicated, as the AST's attributes must be set very precisely. This is problematic for e.g. method invocations.

As the backend is split into ever increasing number of components, there's also some code duplication (e.g. Lower and TransPatterns both have `makeNull()` and `makeLit()`).

It would be good to investigate if we could reduce complexity and code duplication at the backend by introducing better tooling/utilities for common tasks. This could include method invocations and invoke dynamic setup.