In the humanres component, we can create an employee through the form https://localhost:8443/humanres/control/NewEmployee .
This form has required fields that are not the same requirement than the service called when submitting the form.
The service called is createEmployee.
In the service, everything is declared optional but the postalAddContactMechPurpTypeId (which is set in the form as an hidden field).
This means we could create an Employee without forcing a telephone number or a primary address or even a first name.
But then, within the service, a check is done on the firstName and lastName parameters and if missing, an error shows up.
We could harmonize things a little.