code: public Collection<Epic> getBlockedEpics(
              EpicFilter filter) {
          filter = (filter != null) ? filter : new EpicFilter();
  
          filter.blockingIssues.clear();
          filter.blockingIssues.add(this);
          return getInstance().get().epics(filter);
      }
docs: Epics that cannot be completed because of this Issue.
  
  @param filter Criteria to filter epics on.
  @return A collection epics cannot be completed because of
  this Issue filtered by the passed in filter.