.NET Clones a collection in a way that is safe even it if it null.

IEnumerableExtensions.cs

namespace Extensions
{
    /// <summary>
    /// Extension methods for classes that implement the <see cref="IEnumerable"/> interface.
    /// </summary>
    public static class IEnumerableExtensions
    {
        /// <summary>
        /// Clones the list in a way that is safe even it if it null.
        /// </summary>
        /// <typeparam name="TU">The type of items in the list.</typeparam>
        /// <param name="source">The source.</param>
        /// <returns>
        /// A deep copy of <b>param</b> or null.
        /// </returns>
        public static IEnumerable<TU> NullSafeClone<TU>(this IEnumerable<TU> source) where TU : class, ICloneable
        {
            if (null == source)
            {
                yield break;
            }

            foreach (TU obj in source)
            {
                yield return (TU)obj.Clone();
            }
        }
    }
}