Description of problem:
Tab completion don't work correctly.

How reproducible:
Always

Steps to Reproduce:

/extension=org.wildfly.extension.elytron:add
/subsystem=elytron:add
reload
/subsystem=elytron/simple-permission-mapper=login-permission-mapper2:add(permission-mappings=[{roles=[{role<TAB>

Actual results:

• java.lang.IllegalArgumentException
• Details:

  [mkopecky@dhcp-10-40-5-171 bin]$ ./jboss-cli.sh -c
  [standalone@localhost:9990 /] /extension=org.wildfly.extension.elytron:add
  {
      "outcome" => "success",
      "result" => [("elytron" => "1.0.0")]
  }
  [standalone@localhost:9990 /] /subsystem=elytron:add
  {
      "outcome" => "success",
      "response-headers" => {
          "operation-requires-reload" => true,
          "process-state" => "reload-required"
      }
  }
  [standalone@localhost:9990 /] reload
  [standalone@localhost:9990 /] /subsystem=elytron/simple-permission-mapper=login-permission-mapper2:add(permission-mappings=[{roles=[{roleException in thread "Aesh Process Loop 21849810" java.lang.IllegalArgumentException
  	at org.jboss.dmr.ModelValue.getKeys(ModelValue.java:139)
  	at org.jboss.dmr.ModelNode.keys(ModelNode.java:1378)
  	at org.jboss.as.cli.impl.ValueTypeCompleter$ValueTypeCallbackHandler.getCandidates(ValueTypeCompleter.java:502)
  	at org.jboss.as.cli.impl.ValueTypeCompleter.complete(ValueTypeCompleter.java:332)
  	at org.jboss.as.cli.operation.OperationRequestCompleter.complete(OperationRequestCompleter.java:254)
  	at org.jboss.as.cli.operation.OperationRequestCompleter.complete(OperationRequestCompleter.java:74)
  	at org.jboss.as.cli.CommandCompleter.doComplete(CommandCompleter.java:134)
  	at org.jboss.as.cli.CommandCompleter.complete(CommandCompleter.java:63)
  	at org.jboss.as.cli.impl.Console$Factory$1$1.complete(Console.java:143)
  	at org.jboss.aesh.console.AeshCompletionHandler.complete(AeshCompletionHandler.java:155)
  	at org.jboss.aesh.console.AeshInputProcessor.complete(AeshInputProcessor.java:423)
  	at org.jboss.aesh.console.AeshInputProcessor.parseOperation(AeshInputProcessor.java:165)
  	at org.jboss.aesh.console.Console.processInternalOperation(Console.java:773)
  	at org.jboss.aesh.console.Console.execute(Console.java:733)
  	at org.jboss.aesh.console.Console.access$900(Console.java:73)
  	at org.jboss.aesh.console.Console$6.run(Console.java:642)
  	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  	at java.lang.Thread.run(Thread.java:745)
  [mkopecky@dhcp-10-40-5-171 bin]$ 
  

Expected results:
No exception