abstract class A<T>{ abstract <S> S foo(S x, S y); <S extends Number & Comparable<? extends Number>> void baz(A<S> a){} void bar(A<Long> x, A<Integer> y){ baz(foo(x, y)); } } abstract class A1<T>{ abstract <S> S foo(S x, S y); <T extends Number & Comparable<?>, S extends Number & Comparable<? extends T>> void baz(A1<S> a){} void bar(A1<Long> x, A1<Integer> y){ baz(foo(x, y)); } } abstract class A3<T>{ abstract <S> S foo(S x, S y); <S extends Number & Comparable<? extends K>, K extends Number & Comparable<? extends M>, M extends Number & Comparable<?>> void baz(A<S> a){} void bar(A<Long> x, A<Integer> y){ baz(foo(x, y)); } }