protected override Expression <Func <BaseListAssociation, bool> > FindExisting(BaseListAssociation record)
 => existing
 => existing.BaseTypeId == record.BaseTypeId &&
 existing.BaseListId == record.BaseListId;
        protected override IEnumerable <object> EnumerateReferences(BaseListAssociation record)
        {
            yield return(record.BaseType);

            yield return(record.BaseList);
        }