The @Converter annotation and the Attribute Converter interface have two big benefits:

1) They make it possible to persist any as-yet-unsupported java types that do not implement (If they do, it is possible to persist them automatically by turning on the <persist serialization="true" /> option in the objectdb.conf file). 

2) They also make it possible to persist custom objects that are fundamental to your domain in an efficient manner. 

Java tutor & consultant / ret'd middleware, utility, gui, firmware and application software engineer / storage, blu-ray, iTV (30 yrs)