* @summary check that default overrides are properly type-checked

 * @compile/fail/ref=Neg09.out -Werror -Xlint:unchecked -XDrawDiagnostics Neg09.java

 */

import java.util.List;

class Neg09 {

    interface I {

        default List<String> m() { return null; }

    }

    static class C1 {

        public List m() { return null; } //unchecked (return) override

    }

    static class C2 extends C1 implements I { }

    static class C3 implements I {

        public List m() { return null; } //unchecked (return) override

    }

}