The bean session manages the RDF types, which are multi-valued.

If a user specifies a mapping and a single-valued property with predicate RDF.TYPE, then

• saving the bean works, since ThingSession preserves multiple values.
• fetching the bean after a save, however, will invoke Thing.getValue() which is single-valued. One of the RDF types will be selected at random (as per contract)
• saving the bean replaces all the RDF types with the single value.

(Thanks to Shawn, who discovered this.)

At issue is the fact that RDF type is managed especially as a multi-valued type. The implementation, however, does no checking for setValue(Rdf.TYPE, xxx).

Solution:

• make the appropriate note in the documentation for Thing.setValue, Thing.addValue that there are specific calls for managing the type and to use those.

• have BeanMappings refuse to accept property with predicate of Rdf.TYPE.