Description of problem:
Changing an async-handler queue length does not work.

Version-Release number of selected component (if applicable):
EAP 6.1.DR4

How reproducible:
Always

Steps to Reproduce:
1. With EAP admin console create an aync-handler under the logging subsystem
2. Then edit the properties to change the queue length
3. Save
  
Actual results:
Queue length unchanged without error message.

Expected results:
Queue length should have been updated

Additional info:
It also doesn't work through the CLI:

[standalone@localhost:10631 async-handler=ASYNC] :write-attribute(name=queue-length,value=511)
{
    "outcome" => "failed",
    "failure-description" => "JBAS014746: queue-length may not be null",
    "rolled-back" => true
}