Description of problem:
When engine tries to update direct LUN disk after editing it getting the following error in the UI
"Error while executing action Edit VM Disk properties: Internal Engine Error"

and java.lang.ClassCastException in the engine.log

Version-Release number of selected component (if applicable):
is8

How reproducible:
100%

Steps to Reproduce:
1.Create VM with direct LUN disk.
2.Edit direct LUN disk (for example choose "Is shareable")
3.Click "OK"

Actual results:
Getting Internal engine error in UI and exception in engine.log

Expected results:
disk successfully updated

Additional info:
engine.log file attached.