public String queryParam(String queryParamName) {
        return optionalQueryParam(queryParamName).orElse(null);
    }
@Test
    void testRequestUrlQueryParamWhichIsPresentUsingClass() {
        RequestUrl requestUrl = new MatchUrl("/api/jobs?state=SCHEDULED").toRequestUrl("/api/jobs");
        assertThat(requestUrl.queryParam("state", StateName.class, ENQUEUED)).isEqualTo(SCHEDULED);
    }