code: public static void setLocation(HttpServletRequest request, HttpServletResponse response, String location) {
  		if(request.getAttribute(IS_INCLUDED_REQUEST_ATTRIBUTE_NAME) == null) {
  			// Not included, setHeader directly
  			response.setHeader("Location", location);
  		} else {
  			// Is included, set attribute so top level tag can perform actual setHeader call
  			request.setAttribute(LOCATION_REQUEST_ATTRIBUTE_NAME, location);
  		}
  	}
docs: Sets a Location header.  When not in an included page, calls setHeader directly.
  When inside of an include will set request attribute so outermost include can call setHeader.