docs: private List<Entry> siblingsAndBelow(Entry oEntry) {
          if (oEntry == null) return Collections.emptyList();
  
          List<Entry> output = new LinkedList<>();
          for (Entry entry : getCycle(oEntry)) {
              if (entry != null) {
                  output.add(entry);
                  output.addAll(siblingsAndBelow(entry.oFirstChild));
              }
          }
  
          return output;
      }