public Enumeration<String> getAttributeNames() {
        return Collections.enumeration(parent.context().keySet());
    }
@Test
    void testGetAttributeNames() {
        URI uri = URI.create("http://localhost:8080/test");
        HttpRequest httpReq = newRequest(uri, HttpRequest.Method.GET, HttpRequest.Version.HTTP_1_1);
        DiscFilterRequest request = new DiscFilterRequest(httpReq);
        request.setAttribute("some_attr_1", "some_value1");
        request.setAttribute("some_attr_2", "some_value2");

        Enumeration<String> e = request.getAttributeNames();
        List<String> attrList = Collections.list(e);
        assertEquals(2, attrList.size());
        assertTrue(attrList.contains("some_attr_1"));
        assertTrue(attrList.contains("some_attr_2"));

    }