Description of problem:
 NullPointerException is thrown once using tab complete on "data-source --name=ExampleDS a"

Version-Release number of selected component (if applicable):
 EAP 6.2.0.ER5

How reproducible:
 always


Steps to Reproduce:
 1. Start out-of-box standalone.
 2. Connect to CLI 
 3. Enter (it is important to enter some char after datasource name): 
   - [standalone@localhost:9999 /] data-source --name=ExampleDS a
 4. Press TAB

Actual results:
 [standalone@localhost:9999 /] data-source --name=ExampleDS ajava.lang.NullPointerException
	at org.jboss.as.cli.operation.OperationRequestCompleter.complete(OperationRequestCompleter.java:145)
	at org.jboss.as.cli.CommandCompleter.complete(CommandCompleter.java:95)
	at org.jboss.as.cli.impl.Console$Factory$1$1.complete(Console.java:102)
	at org.jboss.aesh.console.Console.complete(Console.java:1151)
	at org.jboss.aesh.console.Console.parseOperation(Console.java:550)
	at org.jboss.aesh.console.Console.read(Console.java:452)
	at org.jboss.aesh.console.Console.read(Console.java:346)
	at org.jboss.as.cli.impl.Console$Factory$1.readLine(Console.java:178)
	at org.jboss.as.cli.impl.CommandContextImpl.interact(CommandContextImpl.java:1200)
	at org.jboss.as.cli.impl.CliLauncher.main(CliLauncher.java:263)
	at org.jboss.as.cli.CommandLineMain.main(CommandLineMain.java:34)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.jboss.modules.Module.run(Module.java:292)
	at org.jboss.modules.Main.main(Main.java:455)


Expected results:
 Nothing is displayed