@Override
 public void setPropertyOnUser(User user, String propertyName, Object value) {
   if (user instanceof SystemUser) {
     throw new VisalloException("Cannot set properties on system user");
   }
   ((InMemoryUser) user).setProperty(propertyName, value);
 }
 @Override
 protected void internalSetPrivileges(User user, Set<String> privileges, User authUser) {
   ((InMemoryUser) user).setPrivileges(privileges);
 }
 @Override
 public void internalRemoveAuthorization(User user, String auth, User authUser) {
   ((InMemoryUser) user).removeAuthorization(auth);
 }