Determine generic nature of targeted methods in J.MethodInvocation

[MBoegers]

What problem are you trying to solve?

For any method targeted by a J.MethodInvocation it should be easy to determine if the method's return type is generic.
This is needed in some cases to implement migrations for language features.
As generics introduce a whole new level of complexity, it should be easy to leave such invocations untouched.

class Test {
    void tst() {
        Object o;
        String some = new GenericClazz<String>().cast(o);  // <1>
        String someStr = new GenericClazz<String>().hashIt("Just a Tests"); // <2>
        String other = StaticClazz.cast(o); // <3>
    }
}

class GenericClazz<T> {
    T cast(Object O) {}
    String hashIt(T t) {}
}

class StaticClazz {
    static <T> T cast(Object o) {}
}

Bullets 1 and 2 are somehow decidable by analyzing the owning class or the parameters of the method.
For Bullet 3 the information are lost, as @knutwannheden describes here it is somehow decideable.

Describe the solution you'd like

I'd like to be able to get the information from the J.MethodInvocation#getMethodType.
Maybe a new Flag would solve this problem and could also be used as shorthand around J.ClassDeclarations.

Have you considered any alternatives or workarounds?

See https://rewriteoss.slack.com/archives/C01A843MWG5/p1732217494169589

Additional context

Are you interested in contributing this feature to OpenRewrite?

Yes