### Question:
CityService { @Transactional public String printAllEmfsInAllCities() { var cities = this.cityRepository.findAllBy(); var emps = cities.stream().map(City::getDepartments) .flatMap(Set::stream) .map(Department::getEmployees) .flatMap(Set::stream) .map(Employee::getName) .collect(Collectors.joining(",")); return emps; } CityService(CityRepository cityRepository); @Transactional String printAllEmfsInAllCities();  }### Answer:
@Test public void test_PrintCities_ExceptSuccess() { var emps = this.cityService.printAllEmfsInAllCities(); System.out.println(emps); Assert.assertNotNull(emps); }