docs: public Stream<? extends TrieNode> getChildren() {
      if (getData().firstChildIndex >= 0) {
        return IntStream.range(0, getData().numberOfChildren)
          .mapToObj(i -> new TrieNode(this.trie, getData().firstChildIndex + i, TrieNode.this));
      }
      else {
        return Stream.empty();
      }
    }