public User(UserId id, String name, ServerGuid serverId) {
checkNotNull(id, "id");
checkNotNull(name, "name");
this.id = id;
this.serverId = serverId;
this.propertyService = new PropertyService(this);
this.userName = propertyService.newProperty(USER_NAME, name);
this.userName.setAllowsNull(false);
this.firstName = propertyService.newProperty(FIRST_NAME);
this.lastName = propertyService.newProperty(LAST_NAME);
this.password = propertyService.newProperty(PASSWORD);