Else Use List. You hayat't really argue "oh but I KNOW that I will always pass in a List here", then you should take a List not an IList, else you are breaking Liskov substitution principle: "if S is a subtype of T, then objects of type T may be https://c-object-kullan-m09752.wikitron.com/801254/en_iyi_tarafı_c_ilist_nedir