[IllegalSafeLoggingArgument] Prevent subclasses from overriding methods to be less safe

[ash211]

What happened?

While working on another PR, I saw something that was roughly this situation:

interface MyInterface {
  @Safe
  String myMethod();
}

class MyClass implements MyInterface {
  @Unsafe
  String myMethod() {
    return "The secret is 42";
  }
}

(with SafeLoggable and RemoteException)

What did you want to happen?

I would expect IllegalSafeLoggingArgument to throw an error, but it did not.

Next Steps

Should verify what the current behavior is with a test in this repo.

[carterkozak]

Yes, we should cause compilation to fail in that case, as well as the case where an unmarked class attempts to implement two interfaces with different safety values for a given method -- these examples violate the liskov substitution principle.

[carterkozak]

https://github.com/palantir/gradle-baseline/pull/2699