ItemCanBeNullAttribute Class

Can be applied to symbols of types derived from IEnumerable as well as to symbols of Task and Lazy classes to indicate that the value of a collection item, of the Task.Result property or of the Lazy.Value property can be null.

[AttributeUsageAttribute]
public sealed class ItemCanBeNullAttribute : Attribute

<AttributeUsageAttribute> _
Public NotInheritable Class ItemCanBeNullAttribute _
	Inherits Attribute

[AttributeUsageAttribute]
public ref class ItemCanBeNullAttribute sealed : public Attribute

public void Foo([ItemCanBeNull]List<string> books)
{
foreach (var book in books)
{
// Warning: Possible 'System.NullReferenceException'
Console.WriteLine(book.ToUpper());
}
}