@Override
 public String getAsString(FacesContext arg0, UIComponent arg1, Object arg2) {
   return GsonUtil.getToString(arg2, AppUser.class);
 }
 @Override
 public String toString() {
   return GsonUtil.getToString(this, RequestDTO.class);
 }
 @Override
 public Object getAsObject(FacesContext arg0, UIComponent arg1, String arg2) {
   return GsonUtil.getFromObject(arg2, AppUser.class);
 }