Re: Collection (or Map) relationships and null

[Abe White]

1. Loaded instances last stored with a null or empty collection/map  
are restored with an empty collection/map, period.  You can ignore  
all the talk about null indicators.
2.  Instances you construct yourself will maintain their null vs.  
empty field values at least until persist.  Beyond that you shouldn't  
rely on null collections and maps remaining null -- they might become  
empty.
3. Pinaki's tip shows how to tell OpenJPA to throw an exception if  
you attempt to add an entity of the wrong type to a persistent  
collection/map field. 
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