code: public static String extractAeroGearSenderInformation(final HttpServletRequest request) {
          String client = request.getHeader("aerogear-sender");
          if (hasValue(client)) {
              return client;
          }
          // if there was no usage of our custom header, we simply return the user-agent value
          return request.getHeader("user-agent");
      }
docs: Reads the "aerogear-sender" header to check if an AeroGear Sender client was used. If the header value is NULL
  the value of the standard "user-agent" header is returned
  
  @param request to inspect
  
  @return value of header