code: public Collection<SecondaryWorkitem> getSecondaryWorkitems(
              SecondaryWorkitemFilter filter) {
  
          if (filter == null) {
              filter = new SecondaryWorkitemFilter();
          }
  
          filter.parent.clear();
          filter.parent.add(this);
  
          return getInstance().get().secondaryWorkitems(filter);
      }
docs: Collection of Tasks and Tests that belong to this primary workitem.
  
  @param filter How to filter the secondary workitems. To get only Tasks,
  pass a TaskFilter. To get only Tests, pass a TestFilter.
  @return Collection of Tasks and Tests that belong to this primary
  workitem.