public void setSpecialAttribute(Attribute attribute, String specialName) {
   AttributeRole oldRole = findRoleBySpecialName(specialName);
   if (oldRole != null) {
     remove(oldRole);
   }
   if (attribute != null) {
     remove(attribute);
     AttributeRole role = new AttributeRole(attribute);
     role.setSpecial(specialName);
     ;
     add(role);
   }
 }