simplify hide headers line

2.Common_services/5.Nginx/vhost_cache.conf

@@ -51,9 +51,7 @@ server {
             proxy_cache_use_stale updating;
             # ignore upstream headers
             # http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_cache_valid
-            proxy_ignore_headers Cache-Control;
-            proxy_ignore_headers X-Accel-Expires;
-            proxy_ignore_headers Expires;
+            proxy_ignore_headers "Cache-Control" "X-Accel-Expires" "Expires";
             # hide upstream X-Cache header
             proxy_hide_header X-Cache;
             # add own X-Cache header
@@ -83,10 +81,7 @@ server {
             # instruct browser to cache this
             expires 7d;
             # headers
-            proxy_ignore_headers Cache-Control;
-            proxy_ignore_headers Set-Cookie;
-            proxy_ignore_headers X-Accel-Expires;
-            proxy_ignore_headers Expires;
+            proxy_ignore_headers "Cache-Control" "X-Accel-Expires" "Expires";
             add_header X-Cache $upstream_cache_status;
         }
     }