paramMap = filter.parseQueryString("=", "UTF-8");
        assertEquals(1, paramMap.size());
        assertEquals("", paramMap.get("")[0]);

    }

    @Test
    public void test_decode() throws IOException {
        final EncodingFilter filter = new EncodingFilter();
        Map<String, String[]> paramMap;

        paramMap = filter.parseQueryString("a=%E3%83%86%E3%82%B9%E3%83%88", "UTF-8");