code: public void scan(HttpMessage msg, NameValuePair originalParam) {
          scan(msg, originalParam.getName(), originalParam.getValue());
      }
docs: General method for a specific Parameter scanning, which allows developers
  to access all the settings specific of the parameters like the place/type
  where the name/value pair has been retrieved. This method can be overridden
  so that plugins that need a more deep access to the parameter context can
  benefit about this possibility.
  @param msg a copy of the HTTP message currently under scanning
  @param originalParam the parameter pair with all the context informations