Здравствуйте, ojow, Вы писали:

[skipped]
Не очень кошерно, но может так?

package ru.rsdn.generics;

import org.junit.Test;

public class TestGenerics {
    public interface Copyable<T extends Copyable<? super T>> {
        void copy(T t);
    }

    public class A implements Copyable<A> {
        protected final String a = "--A--";

        public void copy(A t) {
            System.out.println(t.a);
        }
    }

    public class B extends A {
        private final String b = "--B--";

        // it's not override
        public void copy(B t) {
            super.copy(t);
            System.out.println(t.b);
        }
    }

    @Test
    public void testCopy() {
        final A a0 = new A();
        final A a1 = new A();
        a0.copy(a1);
        final A a = new A();
        final B b = new B();
        a.copy(b);
        final B b0 = new B();
        final B b1 = new B();
        b0.copy(b1);
    }
}