How to create ArrayList type of Varible in Workflow to receive ArrayList object in expression robot

Hi All,

in one of my requirement, i am passing a change object to a custom class, and then want to receive a ArrayList object in workflow expression robot.

how i can create Variable of ArrayList type.

i tried to create it, but while doing check syntax in workflow, it gives me below error.

"wt.util.WTException: ATTENTION: Only Evolvable or Persistable classes can be set as workflow variables.

Nested exception is: wt.util.WTException: ATTENTION: Only Evolvable or Persistable classes can be set as workflow variables."

Please let me know how i can tackle this.

Regards,

Vivek