code: public Collection<Epic> getChildEpics(EpicFilter filter) {
          filter = (filter != null) ? filter : new EpicFilter();
          filter.parent.clear();
          filter.parent.add(this);
          return getInstance().get().epics(filter);
      }
docs: Epics that are immediate children of this Epic.
  
  @param filter Limit the epic returned (If null, then all items returned).
  @return A collection epics that belong to this epic filtered by the
  passed in filter.