Adding Custom Datetype in EMF model gives error :The DateConversionDelegate annotation with key ''format" contains bad value

Question

I am trying to add a Custom DataType to my EMF model, basically I want to add java LocalDate (or alternatively joda LocalDate).

So I am following the instruction here

https://wiki.eclipse.org/EMF/Recipes#Recipe:_Generating_data_types_that_support_date.2Ftime_format

everything is just like in the tutorial , but I when I try to generate the model code it gives me that error (in title). Any ideas ?