int slen = s.length();
      for (int index = 0; index < slen; index++) {
        char c = s.charAt(index);
        if (c < replacements.length && replacements[c] != null) {
          return escapeSlow(s, index);
        }
      }
      return s;
    }

    @Override
    protected char @Nullable [] escape(char c) {
      return c < replaceLength ? replacements[c] : null;
    }
  }

   */
  @Override
  public String escape(String string) {
    checkNotNull(string);
    int end = string.length();
    int index = nextEscapeIndex(string, 0, end);
    return index == end ? string : escapeSlow(string, index);
  }

  /**
   * Scans a sub-sequence of characters from a given {@link CharSequence}, returning the index of
   * the next character that requires escaping.
   *