private static int ftypeKind(Class<?> ftype) {
   if (ftype.isPrimitive()) return Wrapper.forPrimitiveType(ftype).ordinal();
   else if (VerifyType.isNullReferenceConversion(Object.class, ftype)) return FT_UNCHECKED_REF;
   else return FT_CHECKED_REF;
 }
 @Override
 Object checkCast(Object obj) {
   return fieldType.cast(obj);
 }