if (collectionName == null) {
throw ctxt.instantiationException(DBRef.class,
"DBRef contains no collection name");
}
JacksonDBCollection coll = ((JacksonDBCollectionProvider) jp)
.getDBCollection();
JacksonDBCollection<T, K> refColl = coll.getReferenceCollection(
collectionName, type, keyType);
return new FetchableDBRef<T, K>(id, refColl);
} else {
throw ctxt.instantiationException(DBRef.class,
"DBRef can only be deserialised by this deserializer if parser implements "