MINOR: Upgrade jetty to 9.4.30.v20200611 and jersey to 2.31

[Konstantine Karantasis (kkonstantine)]

Align versions with AK.

[Deleted user (ghost)]

Confluent Inc. (@confluentinc) It looks like Konstantine Karantasis (@kkonstantine) just signed our Contributor License Agreement. 👍

Always at your service,

clabot

[Ismael Juma (ijuma)]

LGTM, thanks.

[Konstantine Karantasis (kkonstantine)]

We are hitting an issue with an incompatible change in jetty described here:
jetty/jetty.project#4693
This change (the renaming of closeOutput to completeOutput is reverted in more recent versions).
Oldest version that has a fix is: jetty-9.4.28.v20200408 by looking at https://github.com/eclipse/jetty.project/releases
Probably best to upgrade to this version or newer instead of 9.4.27.v20200227

Wdyt Ismael Juma (@ijuma) ?

[Ismael Juma (ijuma)]

Konstantine Karantasis (@kkonstantine) The jersey upgrade was supposed to have fixed that since 9.4.27 is what they actually test it according to the submitter.

[Konstantine Karantasis (kkonstantine)]

I see. I didn't check jersey. But we are hitting an issue in SR where the jetty method Response#closeOutput is used directly from jetty.

[Konstantine Karantasis (kkonstantine)]

The build is now passing with jetty version 9.4.30.v20200611.

Ismael Juma (@ijuma) if we are good to go here, I'll merge and submit a PR in AK to align the versions there as well.

[Ismael Juma (ijuma)]

LGTM, thanks.

[Konstantine Karantasis (kkonstantine)]

The equivalent PR in AK has been merged: apache/kafka#8893
Aligning the versions here too. Thanks Ismael Juma (@ijuma) Ewen Cheslack-Postava (@ewencp)