Support @Bean 'lite' mode when no @Bean methods are declared locally

[quaff]

ConfigurationClassUtils should check bean methods in super classes also
Fix GH-30449

[quaff]

Test case added, could you review it? @jhoeller @sbrannen

[jhoeller]

This is not within the intentions of our configuration class check which may literally apply to every bean in an application context. Driven by the fact that we're typically introspecting class files in a classpath scan there, not fully resolved classes, we intentionally do not rely on the superclass/interface hierarchy of such beans. We only search for @Bean methods on superclasses and interfaces if there is an indication on the given class to begin with, either a stereotype or local @Bean methods. With the latter local method check, we're just trying to be lenient; in the original version of that code, we insisted on a stereotype for any lite configuration class. I'm afraid we cannot be even more lenient than that when that would incur significant extra parsing cost.

[quaff]

I'm afraid we cannot be even more lenient than that when that would incur significant extra parsing cost.

I don't think it would incur significant extra parsing cost since it's a rare case, at least document should be improved if you insist.