docs: public SortedSet<Entry> getChildEntries() throws IOException {
          if (children == null) {
              if (isFile() || rootNodeDId == -1) {
                  children = NO_CHILDREN;
              }
              else {
                  // Start at root node in R/B tree, and read to the left and right,
                  // re-build tree, according to the docs
                  children = Collections.unmodifiableSortedSet(document.getEntries(rootNodeDId, this));
              }
          }
  
          return children;
      }