Jetty 9.4.3.v20170317 refuses to set an empty HTTP header, leading to cryptic client errors since Hudson-Duplex is missing.
@@ -153,7 +153,7 @@ public abstract class FullDuplexHttpService {
// the actual authentication for the connecting Channel is done by CLICommand
UUID uuid = UUID.fromString(req.getHeader("Session"));
- rsp.setHeader("Hudson-Duplex", ""); // set the header so that the client would know
+ rsp.setHeader("Hudson-Duplex", "true"); // set the header so that the client would know
if (req.getHeader("Side").equals("download")) {
FullDuplexHttpService service = createService(req, uuid);
