code: public static String filter( String message ) {
  
          if (message == null) {
              return (null);
          }
  
          char content[] = new char[message.length()];
          message.getChars(0, message.length(), content, 0);
          StringBuilder result = new StringBuilder(content.length + 50);
          for (int i = 0; i < content.length; i++) {
              switch (content[i]) {
                  case '<':
                      result.append("&lt;");
                      break;
                  case '>':
                      result.append("&gt;");
                      break;
                  case '&':
                      result.append("&amp;");
                      break;
                  case '"':
                      result.append("&quot;");
                      break;
                  default:
                      result.append(content[i]);
              }
          }
          return (result.toString());
  
      }
docs: Filter the specified message string for characters that are sensitive in HTML. This avoids potential attacks caused by
  including JavaScript codes in the request URL that is often reported in error messages.
  
  @param message The message string to be filtered
  @return the filtered message