public List<String> getHeaderNamesAsList() { return new ArrayList<>(parent.headers().keySet()); }
@Test
    void testGetHeaderNamesAsList() {
        URI uri = URI.create("http://localhost:8080/test");
        HttpRequest httpReq = newRequest(uri, HttpRequest.Method.GET, HttpRequest.Version.HTTP_1_1);
        httpReq.headers().add(HttpHeaders.Names.CONTENT_TYPE, "multipart/form-data");
        httpReq.headers().add("header_1", "value1");
        httpReq.headers().add("header_2", "value2");
        DiscFilterRequest request = new DiscFilterRequest(httpReq);

        assertNotNull(request.getHeaderNamesAsList());
        assertEquals(request.getHeaderNamesAsList().size(), 3);
    }