Do you search a plug-in able to generate the Java code that creates instances of PieceOfFurniture, Wall, Room... classes then calls their setters according to user's actions in the plan? It doesn't exist and sorry, but I don't see what it could be useful for...
If you want to follow the creation and modifications of objects, you should add listeners to Home and other classes instances. If you look for an example, read addModelListeners method in PlanComponent class.