System.Collections.ObjectModel.Collection<Τ> & AddRange

Μίας και System.Collections.ObjectModel.Collection<Τ> δεν έχει τη μέθοδο AddRange τη πρόσθεσα και παραθέτω το κώδικα:

using System.Collections.Generic;

namespace MyCompany.SystemExtra.CollectionsExtra.ObjectModelExtra
{
    /// <summary>
    /// Provides the base class for a generic collection.
    /// Support AddRange method.
    /// </summary>
    /// <typeparam name="T">The type of elements in the collection.</typeparam>
    public class Collection<T> : System.Collections.ObjectModel.Collection<T>
    {
        /// <summary>
        /// Adds the elements of the specified collection to the end of the Collection.
        /// </summary>
        /// <param name="elements">The collection whose elements should be added to the end of the Collection. 
        /// The collection itself cannot be a null reference (Nothing in Visual Basic),
        /// but it can contain elements that are a null reference (Nothing in Visual Basic),
        /// if type T is a reference type.</param>
        public void AddRange(IEnumerable<T> elements) {
            if (elements == null) return;
            foreach (T element in elements)
                Add(element);
        }
    }
}