public <T> HttpResponse<T> httpRequest(String url, String method, HttpHeaders headers, Object requestBodyData,
                                                  TypeReference<T> responseFormat) {
        return httpRequest(url, method, headers, requestBodyData, responseFormat, null, null);
    }
@Test
    public void testNullUrl() {
        RestClient client = spy(new RestClient(null));
        assertThrows(NullPointerException.class, () -> {
            client.httpRequest(
                    null,
                    TEST_METHOD,
                    null,
                    TEST_DTO,
                    TEST_TYPE,
                    MOCK_SECRET_KEY,
                    TEST_SIGNATURE_ALGORITHM
            );
        });
    }