docs: private void checkAnonymous(FieldDescriptorDef fieldDef, String checkLevel) throws ConstraintException
      {
          if (CHECKLEVEL_NONE.equals(checkLevel))
          {
              return;
          }
  
          String access = fieldDef.getProperty(PropertyHelper.OJB_PROPERTY_ACCESS);
  
          if (!"anonymous".equals(access))
          {
              throw new ConstraintException("The access property of the field "+fieldDef.getName()+" defined in class "+fieldDef.getOwner().getName()+" cannot be changed");
          }
  
          if ((fieldDef.getName() == null) || (fieldDef.getName().length() == 0))
          {
              throw new ConstraintException("An anonymous field defined in class "+fieldDef.getOwner().getName()+" has no name");
          }
      }