I don't think there is a way to enforce the developer to put annotation on subclass.
However, you can add the required annotations on your parent class and its subclass will "automatically" have the annotation without you explicitly specifying.
@RequiredAnnotations
class Parent{
//...
}
// it will have @RequiredAnnotations without specifying
class Child extend Parent{
//...
}
It works with interface, concrete class or abstract class inheritance.
Like Pedro points out, the @RequiredAnnotation
needs to have @Inherited
to make it work.