/// <summary>
/// Initializes a new instance of the <see cref="ChangeSet"/> class.
/// </summary>
/// <param name="owner">The timeline that owns this change set.</param>
/// <exception cref="ArgumentNullException">
/// Thrown if <paramref name="owner"/> is <see langword="null" />.
/// </exception>
public ChangeSet(Timeline owner)
: this(owner, null)
{
}