The pool can be recreated inside WildFly at every call to reload the server. With that, direct allocated buffers are just lost but, as pointed in the Javadoc of ByteBuffer:
"The contents of direct buffers may reside outside of the normal garbage-collected heap, and so their impact upon the memory footprint of an application might not be obvious. "

An out of memory error can be verified by reloading the WildFly server several times after performing a cli operation, that causes direct buffers to be allocated.