I tried it, though the logs are really full and maybe I missed something but:
When the request starts, this is printed:
2019-05-06 09:42:26.856 [DEBUG] [org.eclipse.jetty.io.IdleTimeout ] - SocketChannelEndPoint@60c17c24{/0:0:0:0:0:0:0:1:42500<->/0:0:0:0:0:0:0:1:8443,OPEN,fill=-,flush=-,to=30000/30000}{io=0/0,kio=0,kro=1}->SslConnection@2bebf775{NOT_HANDSHAKING,eio=-1/-1,di=-1}=>HttpConnection@11589bd4[p=HttpParser{s=END,0 of -1},g=HttpGenerator@778b3edc{s=COMMITTED}]=>HttpChannelOverHttp@66e01ab1{r=1,c=true,a=ASYNC_WAIT,uri=https://URL/rest/sitemaps/events/02416c92-b01e-419f-84b2-cc11e0721fa6?sitemap=home&pageid=01060504,age=439378} idle timeout check, elapsed: 30000 ms, remaining: 0 ms
[...]
2019-05-06 09:42:26.856 [DEBUG] [org.eclipse.jetty.io.IdleTimeout ] - SocketChannelEndPoint@60c17c24{/0:0:0:0:0:0:0:1:42500<->/0:0:0:0:0:0:0:1:8443,OPEN,fill=-,flush=-,to=30000/30000}{io=0/0,kio=0,kro=1}->SslConnection@2bebf775{NOT_HANDSHAKING,eio=-1/-1,di=-1}=>HttpConnection@11589bd4[p=HttpParser{s=END,0 of -1},g=HttpGenerator@778b3edc{s=COMMITTED}]=>HttpChannelOverHttp@66e01ab1{r=1,c=true,a=ASYNC_WAIT,uri=https://URL/rest/sitemaps/events/02416c92-b01e-419f-84b2-cc11e0721fa6?sitemap=home&pageid=01060504,age=439378} idle timeout expired
[...]
2019-05-06 09:42:26.857 [DEBUG] [rg.eclipse.jetty.io.AbstractEndPoint] - Ignored idle endpoint SocketChannelEndPoint@60c17c24{/0:0:0:0:0:0:0:1:42500<->/0:0:0:0:0:0:0:1:8443,OPEN,fill=-,flush=-,to=30001/30000}{io=0/0,kio=0,kro=1}->SslConnection@2bebf775{NOT_HANDSHAKING,eio=-1/-1,di=-1}=>HttpConnection@11589bd4[p=HttpParser{s=END,0 of -1},g=HttpGenerator@778b3edc{s=COMMITTED}]=>HttpChannelOverHttp@66e01ab1{r=1,c=true,a=ASYNC_WAIT,uri=https://URL/rest/sitemaps/events/02416c92-b01e-419f-84b2-cc11e0721fa6?sitemap=home&pageid=01060504,age=439379}
The connection hangs in the browser. When the request times out, the following message is shown:
java.util.concurrent.TimeoutException: Idle timeout expired: 30000/30000 ms
at org.eclipse.jetty.io.IdleTimeout.checkIdleTimeout(IdleTimeout.java:166) [75:org.eclipse.jetty.io:9.4.11.v20180605]
at org.eclipse.jetty.io.IdleTimeout$1.run(IdleTimeout.java:50) [75:org.eclipse.jetty.io:9.4.11.v20180605]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:?]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:?]
at java.lang.Thread.run(Thread.java:748) [?:?]
2019-05-06 09:41:56.862 [DEBUG] [org.eclipse.jetty.io.WriteFlusher ] - ignored: WriteFlusher@687b05a5{IDLE}->null
java.util.concurrent.TimeoutException: Idle timeout expired: 30000/30000 ms
at org.eclipse.jetty.io.IdleTimeout.checkIdleTimeout(IdleTimeout.java:166) [75:org.eclipse.jetty.io:9.4.11.v20180605]
at org.eclipse.jetty.io.IdleTimeout$1.run(IdleTimeout.java:50) [75:org.eclipse.jetty.io:9.4.11.v20180605]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:?]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [?:?]
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:?]
at java.lang.Thread.run(Thread.java:748) [?:?]
Is this of any help?