static L<Method> findNonDefaultInterfaceMethods(Class intrface) {

  if (!isInterface(intrface)) null;

  new L<Method> l;

  _MethodCache cache = getMethodCache(intrface);

  Class c = intrface;

  do {

    for (Method m : c.getDeclaredMethods())

      if (m.getDeclaringClass() != O.class

        && !m.isDefault() && !isStaticMethod(m))

        l.add(m);

    c = c.getSuperclass();

  } while (c != null);

  ret l;

}