AttributeDefinitionForm df = (AttributeDefinitionForm) form;
AttributeDefinition def = (AttributeDefinition) request.getSession().getAttribute(Constants.EDITING_ITEM);
if (def.isSystem()) {
throw new Exception("System attribute definitions may not be edited.");
}
df.initialise(def);
df.setEditing();
df.setReferer(CoreUtil.getReferer(request));
CoreUtil.addRequiredFieldMessage(this, request);
return mapping.findForward("display");
}