This fix tries to address the issue raised in 25927 where
the HTTP headers have been chaged when AUthZ plugin is in
place.
This issue is that in `FlushAll` (`pkg/authorization/response.go`),
the headers have been written (with `WriteHeader`) before all the
headers have bee copied.
This fix fixes the issue by placing `WriteHeader` after.
A test has been added to cover the changes.`
This fix fixes 25927
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Upstream-commit: 9cb8fb6ea03fcd78010ce7dd33585d96cd73e38c
Component: engine
1a72f2bb5c