try {
        defaultFunction.apply(null);
        fail("Proxy Should have rejected null");
      } catch (NullPointerException expected) {
      }
    }
  }

  public void testNullRejectingInterfaceDefaultValue() {
    new NullRejectingInterfaceDefaultValueChecker().check();
  }

  private static class MultipleInterfacesDefaultValueChecker extends DefaultValueChecker {