Related to IFC4! The use of IfcPropertyDefinitionSet in IfcPropertyDefinitionSelect is missing. There is no delegate class generated for IfcPropertyDefinitionSet, but for IfcPropertyDefinition it is. I would expect something like ``` @XpressModel(kind="new", pattern="delegate",select="IfcPropertySetDefinitionSet") class DelegateIfcPropertySetDefinitionSetIfcRelDefinesByProperties extends DelegateIfcRelDefinesByPropertiesIfcPropertySetDefinitionSelect { container IfcPropertySetDefinitionSet relatingPropertyDefinition opposite aSet } ``` to be added [here](https://github.com/Bitub/step-ifc4/blob/master/org.buildingsmart.ifc4/model/IFC4_ADD1.exp.xcore#L16962-L16976)