public void AddEntity(TGroup group, TSubEntity entity)
 {
     if (!SubEntityStaging.ContainsKey(group))
     {
         SubEntityStaging.Add(group, new List <TSubEntity> {
             entity
         });
     }
     else
     {
         SubEntityStaging[group].Add(entity);
     }
 }
 public void Clear()
 {
     ChangeTracker.Clear();
     SubEntityStaging.Clear();
 }