A class contains reference to Application and View which are needed by external command.
Namespace: Autodesk.Revit.UI
Assembly: RevitAPIUI (in RevitAPIUI.dll) Version: 20.0.0.0 (20.0.0.377)
Namespace: Autodesk.Revit.UI
Assembly: RevitAPIUI (in RevitAPIUI.dll) Version: 20.0.0.0 (20.0.0.377)