LazyLoading bug for SPARQL based Attributes

[luxbe]

If the @sparql annotation is used to define an attribute that can be lazily resolved with a SPARQL query, JOPA throws an exception:

@Sparql(
    query = "SELECT ?capacity WHERE { ?x a <http://uob.iodt.ibm.com/univ-bench-dl.owl#Course> . ?x <http://uob.iodt.ibm.com/univ-bench-dl.owl#capacity> ?capacity }",
    fetchType = FetchType.LAZY
)
private Collection<Integer> allCapacity;

Exception in thread "main" java.lang.ClassCastException: class cz.cvut.kbss.jopa.model.metamodel.PluralQueryAttributeImpl cannot be cast to class cz.cvut.kbss.jopa.model.metamodel.PluralAttribute (cz.cvut.kbss.jopa.model.metamodel.PluralQueryAttributeImpl and cz.cvut.kbss.jopa.model.metamodel.PluralAttribute are in unnamed module of loader 'app')
	at cz.cvut.kbss.jopa.proxy.lazy.LazyLoadingProxyFactory.createProxy(LazyLoadingProxyFactory.java:62)
	at cz.cvut.kbss.jopa.sessions.CloneBuilder.populateAttributes(CloneBuilder.java:168)
	at cz.cvut.kbss.jopa.sessions.CloneBuilder.buildCloneImpl(CloneBuilder.java:136)
	at cz.cvut.kbss.jopa.sessions.CloneBuilder.buildClone(CloneBuilder.java:83)
	at cz.cvut.kbss.jopa.sessions.AbstractUnitOfWork.registerExistingObject(AbstractUnitOfWork.java:457)
	at cz.cvut.kbss.jopa.sessions.AbstractUnitOfWork.readObjectInternal(AbstractUnitOfWork.java:288)
	at cz.cvut.kbss.jopa.sessions.AbstractUnitOfWork.readObject(AbstractUnitOfWork.java:272)
	at cz.cvut.kbss.jopa.model.EntityManagerImpl.find(EntityManagerImpl.java:296)
	at cz.cvut.kbss.jopa.model.EntityManagerImpl.find(EntityManagerImpl.java:281)
	at cz.cvut.kbss.jopa.example01.ManualRunner.execute(ManualRunner.java:73)
	at cz.cvut.kbss.jopa.example01.ManualRunner.run(ManualRunner.java:57)
	at cz.cvut.kbss.jopa.example01.Example.main(Example.java:45)