code: private static String unescapeString(String value) {
  
          Matcher matcher = PATTERN_UNESCAPE.matcher(value);
          return matcher.replaceAll("\\\\\\\\$1");
      }
docs: Unescapes the value of a property in a property file to
  be saved correctly in OpenCms.<p>
  
  Mainly handles all escaping sequences that start with a backslash.<p>
  
  @see #escapeString(String)
  
  @param value the value taken form the property file
  
  @return the unescaped string value