This optional parameter defines an SQL query which will be used to determine whether a user is a member of a group in order to implement the Group check item. Special characters are supported. %0 is replaced by the user name being checked. %1 is replaced by the group name being checked. You can use bound variables with GroupMembershipQueryParam. GroupMembershipQuery is expected to return a single row, where the first field is the name of the group the user belongs to.