* @throws NullPointerException if {@code string} is null
   */
  @Override
  public String escape(String string) {
    checkNotNull(string); // GWT specific check (do not optimize)
    // Inlineable fast-path loop which hands off to escapeSlow() only if needed
    int length = string.length();
    for (int index = 0; index < length; index++) {
      if (escape(string.charAt(index)) != null) {
        return escapeSlow(string, index);
      }