https://learn.microsoft.com/ja-jp/dotnet/api/system.windows.markup.contentpropertyattribute.name?view=netframework-4.8.1&viewFallbackFrom=windowsdesktop-10.0
ContentPropertyAttribute.Name Property (System.Windows.Markup) | Microsoft Learn
Gets the name of the property that is the content property.
property systemnamewindowsmarkupmicrosoft