Skip null-safety architecture rule for generated Java sources

[atkawa7]

The null-safety architecture rule currently flags generated Java classes, such as JAXB-generated schema classes, because they are public and do not use JSpecify or Kotlin null-safety annotations. Support skipping @generated

[wakingrufus]

Thanks for the feedback! I am open to excluding @Generated code, however the jakarta.Generated annotation has SOURCE retention, which would not work here, so it could only work if we do a pattern match on any generated annotation, and custom generated annotations with RUNTIME retention were used in code generation