https://learn.microsoft.com/ja-jp/dotnet/api/system.attributeusageattribute.allowmultiple?view=netframework-4.8.1&viewFallbackFrom=net-10.0
AttributeUsageAttribute.AllowMultiple Property (System) | Microsoft Learn
Gets or sets a Boolean value indicating whether more than one instance of the indicated attribute can be specified for a single program element.
property systemmicrosoftlearn