code: public static Iterator iterator(CharSequence trieChars, int offset, int maxStringLength) {
          return new Iterator(trieChars, offset, -1, maxStringLength);
      }
docs: Iterates from the root of a char-serialized BytesTrie.
  @param trieChars CharSequence that contains the serialized trie.
  @param offset Root offset of the trie in the CharSequence.
  @param maxStringLength If 0, the iterator returns full strings.
  Otherwise, the iterator returns strings with this maximum length.
  @return A new CharsTrie.Iterator.