code: protected Set<String> getPermittedAttributes(final IAuthorizationPrincipal principal) {
          final Set<String> attributeNames = personAttributeDao.getPossibleUserAttributeNames();
          return getPermittedAttributes(principal, attributeNames);
      }
docs: Get the set of all user attribute names defined in the portal for which the specified
  principal has the attribute viewing permission.
  
  @param principal
  @return