When field definition is added to the ContentType, all Content instances of that ContentType are updated by adding a field with default value defined in field definition.

As user can be created only through UserService (or User storage handler) and not through external storage, field of the ezuser type added in such a way will not have all data properly created. Most important, it will not be possible to update such a user so that it becomes functional.

Some options here:

1. do not allow adding ezuser field to the ContentType that has existing Content instances
2. handle it as a special case and create non-functional user that can be later updated (Legacy Storage way)
3. something else?