Thanks Mr.Masayuki for your replay .
Yes , you are right i meant abap class method . I have not get any error yet . The thing is that i already created class method for my workflow and as i understand from the documentation that each level approver should be an Activity which have to be assigned to a task and the task should be assign either to BOR or ABAP CLASS . In my case i use ABAP Class , now the outcomes of this activity should equal to the number of action on my fiori application (inbox or Approve request or any ) . The problem is that iam not able to add N required action in the activity that is assigned to abap class task . But in case of BOR they are coming automatically . So how to solve this problem ?
Your time and effort is highly appreciated .