When defining a bunch of rules an engine reload may result in an OOM exception.
To reproduce the issue, simply create a rule which sets the port value to 1-65535 or omits the value completely. Try increasing the number of rules by 5 and watch the memory consumption on each reload of the engine. At some point the JVM runs out of memory. For me it was around 20-25. Please note, that with omnidirectional=true the JVM runs out of memory more quickly.