Hi,
Whenever you are unsure of how to use certain K2 SmartObjects, you can try enabling SmartObject logging, then go perform that action in K2, then check the generated logs for the correct input to use.
For example, i see you are trying to execute the Task SmartObject, GetWorklistItems method. This particular SmartObject and method is used in your K2 Management page > Users > Task List. You can enable SmartObject logging, then go to K2 Management page, fill in all the filters you want, execute the method, then check the brokerpackagein.log to see what is the input being passed into the SmartObject.
Here is a sample of the correct RegularFilters you have to pass in:
[{"ColumnName":"Process Full Name","Condition":"AND","Comparison":"LIKE","ParameterValue":"K2Project1Process"},{"ColumnName":"Event Name","Condition":"AND","Comparison":"LIKE","ParameterValue":"test"},{"ColumnName":"Folio","Condition":"AND","Comparison":"LIKE","ParameterValue":"test"},{"ColumnName":"Destination","Condition":"AND","Comparison":"LIKE","ParameterValue":"K2:DENALLIXob"}]
I filled in the Workflow Name, Event Name, Folio and Destination on the Management's Task List page to obtain the above RegularFilters.