Strip all requests with www subdomain and 301 redirect.

DomainFilters.groovy

class DomainFilters {
  def filters = {
    wwwCheck(uri:'/**') {
      before = {
        if (request.getServerName().startsWith("www.")) {
          int port = request.getServerPort();
          
          if (request.getScheme().equals("http") && port == 80) {
              port = -1;
          } else if (request.getScheme().equals("https") && port == 443) {
              port = -1;
          }
          
          URL redirectURL = new URL(request.getScheme(), request.getServerName().replaceFirst("www.",""), port, request.forwardURI);

          response.setStatus(301)
          response.setHeader("Location", redirectURL.toString())
          response.flushBuffer()
        }
      }
    }
  }
}