[rules-users] Extending objects in declared facts

When a fact is declared with propertyChangeSupport in Guvnor, such as following: declare Hemodynamics @propertyChangeSupport systolicBP: Integer diastolicBP: Integer centralVenousP: Integer wedgeP: Integer status: Boolean alive: Boolean end then the following warning shows up in JBoss console: Warning: Method addPropertyChangeListener not found on the class class makeModelTest.Hemodynamics so Drools will be unable to process JavaBean PropertyChangeEvents on the asserted Object I implement property changes in a model object so would like to be able to say something like: declare Hemodynamics extends ModelObject @propertyChangeSupport systolicBP: Integer diastolicBP: Integer centralVenousP: Integer wedgeP: Integer status: Boolean alive: Boolean end The documentation refers to using Guvnor and declarative facts to extend an object that already exists, but not clear that this can actually be done.