JBAS014746: pool-max-size may not be null

I have an EJB deployed in a WAR. When I want to change the pool size from the deployment I get:

/deployment=perftest-1.0.0.war/subsystem=ejb3/stateless-session-bean=PerfCall:write-attribute(name=pool-max-size,value=30)
{
"outcome" => "failed",
"failure-description" => "JBAS014746: pool-max-size may not be null",
"rolled-back" => true
}

The bug is not severe, since the feature to change the pool-size here seems to be not implemented yet, but the message is confusing (wrong). The pool-size can be changed in the ejb3 subsystem.