public static void setDefaultFactory(InternalLoggerFactory defaultFactory) {
        InternalLoggerFactory.defaultFactory = ObjectUtil.checkNotNull(defaultFactory, "defaultFactory");
    }
@Test
    public void shouldNotAllowNullDefaultFactory() {
        assertThrows(NullPointerException.class, new Executable() {
            @Override
            public void execute() {
                InternalLoggerFactory.setDefaultFactory(null);
            }
        });
    }