The current compiler plants code to create the throwable specified in the throw action but fails to wrap it in a ThrowException before throwing it. This means it is caught by the rule engine and rethrown as an ExecuteException which is then rethrown (as a runtime exception) by the handler code injected into the rule's trigger method. The correct behaviour is for the ThrowException to pass out of the rule engine to the injected handler which unwraps the embedded throwable and rethrows it to the caller of the trigger method.