protected override IEnumerable GetOldCollectionContent(object oldCollection)
 {
     return(oldCollection == null ? null : Toolz.ListToIndexElementPairList((IList)oldCollection));
 }
 protected override IEnumerable GetNewCollectionContent(IPersistentCollection newCollection)
 {
     return(newCollection == null ? null : Toolz.ListToIndexElementPairList((IList)newCollection));
 }