I have an interface called InducedFact. Rules use insertLogical to insert instances of implementing classes, and a working memory listener allows me to control the application when those facts are inserted and removed. However in some cases, the fields of my InducedFact class have been changed to null when my event listener's 'objectRetracted' method is called, although they have been properly initialized upon 'objectInserted'. Even the debugger could not see when the fields were set back to null. I have not been able to create a simple test case to reproduce it, however. Excluding the implementing classes from shadow proxying does solve the problem. However it is a bit inconvenient to have to give the full list of implementing classes (passing the interface name with the code below doesn't work). Also, the rule base may have been serialized, and I would have to recreate it every time I create a new InducedFact implementing class. RuleBaseConfiguration rbConf = new RuleBaseConfiguration(); rbConf.setShadowProxy(true); rbConf.setShadowProxyExcludes(InducedFact.class.getName()); Wouldn't it be more flexible to configure the working memory elsewhere than in the rule base configuration? Thanks in advance for your insights.