Hi Stefano,
My explaination of nextId initialization is totally wrong. PVM didn't use InitializePropertiesCmd to intialize the JBPM4_PROPERTY. In fact, the initialization job is done by CheckDbCmd.
It is very strange for me, because it means if we don't you CheckDbCmd at the first time, e.g. invoke ConfigurationImpl.skipDbCheck(), then the JBPM4_PROPERTY will be empty and the NullPointerException will occure.
Is it a bug of jBPM 4.3?