docs: private void leafEntryIDs(MkAppTreeNode<O> node, ModifiableDBIDs result) {
      if(node.isLeaf()) {
        for(int i = 0; i < node.getNumEntries(); i++) {
          MkAppEntry entry = node.getEntry(i);
          result.add(((LeafEntry) entry).getDBID());
        }
      }
      else {
        for(int i = 0; i < node.getNumEntries(); i++) {
          MkAppTreeNode<O> childNode = getNode(node.getEntry(i));
          leafEntryIDs(childNode, result);
        }
      }
    }