Created attachment 572719 [details]
Exception in server log

Cannot validate or save custom work item without parameters and results in Designer. Or at least I think that it happens due to undefined parameters and results field. I have wrote following work item definition:

[
  [
    "name" : "MyTask",
    "displayName" : "MyTask",
    "icon" : "http://localhost:8080/drools-guvnor/rest/packages/defaultPackage/assets/defaultlogicon/binary",
  ]
]

It is not possible to validate this one. Designer responds "Invalid answer from server". Also it is not possible to save it, because after the save the Designer reloads and all the changes are lost. I have attached an exception from server log.

I would expect that designer work item editor would let me validate my work item definition that I could see existing problems, like in the graphical process designer. I don't know if custom work item can have empty parameters or results, but I think that it should be possible without problems.