@Override
    protected Boolean doInBackground(Integer... integers) {
      try {
        ProfessionalService professionalService = new ProfessionalService(getActivity());
        professionalDTOList =
            professionalService.findProfessionalAndPhoneContactsByCustomerId(customerDTO.getId());
        unavailableProfessionalsSet =
            professionalService.findUnavailableProfessionalsInUpcomingDates(professionalDTOList);
        if (unavailableProfessionalsSet == null) {
          unavailableProfessionalsSet = new HashSet<>();
        }

      } catch (Exception e) {
        e.printStackTrace();
        return false;
      }
      return true;
    }