/// <summary>
/// Determines whether this Freeform is a closed one or an open one.
/// </summary>
/// <param name="cached">if set to <c>true</c> the previously cached result will be returned.</param>
/// <returns>
/// <c>true</c> if the Freeform is a closed one; otherwise, <c>false</c>.
/// </returns>
virtual public bool IsClosed(bool cached = true)
{
if (IsValid() && !cached)
{
_isClosed = PolygonHelper.IsClosedFreeForm(Shape.Shape);
}
return(_isClosed);
}
