Code Inspection: Collection's content is never queried (non-private accessibility)

JetBrains Rider analyzes access to collections created in your code and warns you if a collection is updated but its contents are never used in the entire solution.

All standard collection types are analyzed this way by default. If necessary, you can also apply this analysis to your custom collections that derive from IEnumerable. In this case, you need to tell JetBrains Rider how invocations of collection’s public methods will affect the contents of the collection. To do so, mark the methods of your collection class with the [CollectionAccessAttribute], which should have one of four flags: None, Read, ModifyExisitingContent, UpdatedContent (the difference between the last two flags is that UpdatedContent means that the marked function can also add new elements to the collection). Here is a simple example to illustrate this: