code: public static String unescape(String input, char escapeCharacter) {
        if (input == null) {
           return null;
        }
        StringBuilder builder = new StringBuilder();
        for (int i = 0; i < input.length(); ) {
           if (input.charAt(i) == escapeCharacter) {
              builder.append(input.charAt(i + 1));
              i = i + 2;
           } else {
              builder.append(input.charAt(i));
              i++;
           }
        }
        return builder.toString();
     }
docs: Unescape string.
  
  @param input           the input
  @param escapeCharacter the escape character
  @return the string