Background and Motivation

As it is a best practice for API's to return ReadOnlyCollection<T> instead of List<T> etc, it would be nice to have an easy way to create an empty ReadOnlyCollection<T>. On par with Array.Empty<T>().

As it is also a best practice to return an empty collection instead of null.

Proposed API

public class ReadOnlyCollection<T>
{
    public static ReadOnlyCollection<T> Empty { get; }
}

Usage Examples

public ReadOnlyCollection<Stuff> FindStuff(string filter)
{
    if (string.IsNullOrEmpty(filter)) return ReadOnlyCollection<Stuff>.Empty;
}