public OpenXmlPartRootXElementFeature(OpenXmlPart part)
        {
            _part   = part;
            _events = _part.Features.GetRequired <IPartRootEventsFeature>();

            _events.Change += OnPartRootChange;
        }
 internal static void OnChange(this IPartRootEventsFeature events, EventType type, OpenXmlPart?part)
 {
     if (part is not null && events is IRaiseFeatureEvent <OpenXmlPart> raise)
     {
         raise.OnChange(type, part);
     }
 }