What you are doing seems OK at first glance. Could you enable debug logging for your test and attach the log? Make sure you have DEBUG logging enabled for the type converter impl
You should see be seeing a message when your type converter is loaded like
2009-02-03 10:51:18,549 [main ] DEBUG AnnotationTypeConverterLoader - Loading converter class: my.converter.MyConverter
OK I was able to get it to work.
They converters are null because the context was not started.