A type contains an externally visible member that is a System.Collections.Generic.List type, returns a System.Collections.Generic.List type, or whose signature includes a System.Collections.Generic.List parameter.
System.Collections.Generic.List is a generic collection designed for performance not inheritance and, therefore, does not contain any virtual members. The following generic collections are designed for inheritance and should be exposed instead of System.Collections.Generic.List.
Do not exclude a warning from this rule unless the assembly that raises this warning is not meant to be a reusable library. For example, it would be safe to exclude this warning in a performance tuned application where a performance benefit was gained from the use of generic lists.