JPDL employee manager structure in jbpm 4.3

I have moved from jbpm 3 to jbpm 4.3 but i found that table membership missing one important column ROLE_ which describes the role of the user in the group . i used to set it and use the following expression in jpdl to get the manager

EX : variable(emp_wf_user) --> group(B) --> member(manager)

with no role i can not issue this as an assignment expression