The Above is an IList itself birli this is what seems to be the standard to use with nhibernate. Otherwise I might have returned IEnumberable back but not sure. Still, I emanet't figure out what the user would 100% need(that's where returning a concrete has an advantage over). Found this https://damienfrygm.dgbloggers.com/28426295/c-ilist-nerelerde-kullanılıyor-genel-bakış