/**
  * addRole
  *
  * @param aRole Role
  */
 public void addRole(Role aRole) {
   Element newRole = factory.roleToElement(aRole);
   Element roles = this.getRolesElement();
   roles.appendChild(newRole);
   writeDocument();
 }
 /**
  * addUser
  *
  * @param anUser User
  */
 public void addUser(User anUser) {
   Element newUser = factory.userToElement(anUser);
   Element users = this.getUsersElement();
   users.appendChild(newUser);
   writeDocument();
 }