The CodeGenerator tries to identify an Enum field using toString.
This can fail if the toString method of the field has been customized (e.g. ChronoUnit).

I suppose that the following code

if (unboxedType.isEnum()) {
	getField(unboxedType.getField(((Enum<?>)value).name()));
	return true;
}

considering that name() is the value expected by Enum.valueOf too.