code: @SuppressWarnings("unchecked")
      protected List getUserRoles(DirContext dirContext, String username) throws LoginException,
              NamingException {
          String userDn = _userRdnAttribute + "=" + username + "," + _userBaseDn;
  
          return getUserRolesByDn(dirContext, userDn, username);
      }
docs: attempts to get the users roles from the root context
  
  NOTE: this is not an user authenticated operation
  
  @param dirContext
  @param username
  @return
  @throws LoginException