Refactor to use new helper to send error response

services/git-bridge/src/main/java/uk/ac/ic/wlgitbridge/server/Oauth2Filter.java

@@ -84,11 +84,7 @@ public class Oauth2Filter implements Filter {
         // Reject v1 ids, the request will be rejected by v1 anyway
         if (project.matches("^[0-9]+[bcdfghjklmnpqrstvwxyz]{6,12}$") && !project.matches("^[0-9a-f]{24}$")) {
             Log.info("[{}] Request for v1 project, refusing", project);
-            HttpServletResponse response = ((HttpServletResponse) servletResponse);
-            response.setContentType("text/plain");
-            response.setStatus(404);
-            PrintWriter w = response.getWriter();
-            List<String> l = Arrays.asList(
+            sendResponse(servletResponse, 404, Arrays.asList(
                     "This project has not yet been moved into the new version",
                     "of Overleaf. You will need to move it in order to continue working on it.",
                     "Please visit this project online on www.overleaf.com to do this.",
@@ -98,11 +94,7 @@ public class Oauth2Filter implements Filter {
                     "",
                     "If this is unexpected, please contact us at support@overleaf.com, or",
                     "see https://www.overleaf.com/help/342 for more information."
-            );
-            for (String line : l) {
-                w.println(line);
-            }
-            w.close();
+            ));
             return;
         }
         Log.info("[{}] Checking if auth needed", project);