CriteriaBuilder cb = em.getCriteriaBuilder();
        CriteriaQuery<Data> cq = cb.createQuery(TxData.class);
        Root<Data> obj = cq.from(Data.class);
        cq.select(obj);
        
        MapJoin<Data, String, OtherClass> mj = obj.joinMap("other");

        Path<String> otherKey = mj.key();
        Path<OtherClass> otherItem = mj.get("item");
        
        cq.where(cb.and(
            cb.equal(otherKey,"key"),
            cb.equal(otherItem , "value")));
        
        TypedQuery<Data> tq = em.createQuery(cq);

java.lang.NullPointerException
	at org.hibernate.jpa.criteria.path.AbstractPathImpl.getPathIdentifier(AbstractPathImpl.java:92)
	at org.hibernate.jpa.criteria.path.AbstractPathImpl.render(AbstractPathImpl.java:252)
	at org.hibernate.jpa.criteria.predicate.ComparisonPredicate.render(ComparisonPredicate.java:187)
	at org.hibernate.jpa.criteria.predicate.AbstractSimplePredicate.render(AbstractSimplePredicate.java:65)
	at org.hibernate.jpa.criteria.predicate.CompoundPredicate.render(CompoundPredicate.java:186)
	at org.hibernate.jpa.criteria.predicate.CompoundPredicate.render(CompoundPredicate.java:132)
	at org.hibernate.jpa.criteria.predicate.CompoundPredicate.render(CompoundPredicate.java:122)
	at org.hibernate.jpa.criteria.QueryStructure.render(QueryStructure.java:262)
	at org.hibernate.jpa.criteria.CriteriaQueryImpl.interpret(CriteriaQueryImpl.java:312)
	at org.hibernate.jpa.criteria.compile.CriteriaCompiler.compile(CriteriaCompiler.java:147)
	at org.hibernate.jpa.spi.AbstractEntityManagerImpl.createQuery(AbstractEntityManagerImpl.java:736)

super( criteriaBuilder, javaType, null );