fix tests

Author: lukaszmachaj

src/test/java/com/capgemini/training/appointmentbooking/logic/impl/ManageAppointmentUcImplTest.java

@@ -82,8 +82,8 @@ void shouldBookAppointment() {
         AppointmentEntity appointmentEntity = buildAppointmentEntity(clientId, specialistId, treatmentId, dateTime, status);
 
         when(findAppointmentUc.hasConflictingAppointment(specialistId, dateTime)).thenReturn(false);
-        when(clientRepository.findById(appointmentBookingEto.clientId())).thenReturn(Optional.of(new ClientEntity()));
-        when(treatmentRepository.findById(appointmentBookingEto.treatmentId())).thenReturn(Optional.of(new TreatmentEntity()));
+        when(clientRepository.getReferenceById(appointmentBookingEto.clientId())).thenReturn(new ClientEntity());
+        when(treatmentRepository.getReferenceById(appointmentBookingEto.treatmentId())).thenReturn((new TreatmentEntity()));
         when(appointmentRepository.saveAndFlush(any())).thenReturn(appointmentEntity);
 
         // when