/**
  * Fetches just the Roles associated with the corresponding DefaultUserImpl.
  *
  * @param userId the id of the user
  * @return the DefaultUserImpl's set of Roles or an empty Set.
  */
 public Set<ISecurityRole> getUserRoles(Long userId) {
   checkArgument(userId != null, "getUserRoles() requires a non-null userId parameter.");
   Iterator<UserRolePermissionJoinRow> baseResults =
       isEnabledColumnUsed()
           ? getEnabledUserRolesAndPermissions(userId)
           : getUserRolesAndPermissions(userId);
   DefaultUserImpl u = extractObjectGraphFromJoinResults(baseResults);
   return u != null ? u.getRoles() : Collections.<ISecurityRole>emptySet();
 }
 public Set<ISecurityRole> getUserRoles(String username) {
   DefaultUserImpl u =
       findUser(username); // We'd need to do a 4-way join anyway, so just call findUser()
   return u != null ? u.getRoles() : Collections.<ISecurityRole>emptySet();
 }