avoid xmlstring builder toString

[bgrozev]

• chore: Update jitsi-xmpp-extensions.
• log: Remove System.err logs.
• fix: Avoid using XmlStringBuilder.toString.

[codecov]

Codecov Report

Merging #1118 (1937951) into master (ef49650) will decrease coverage by 0.02%.
The diff coverage is 8.06%.

@@             Coverage Diff              @@
##             master    #1118      +/-   ##
============================================
- Coverage     27.88%   27.86%   -0.02%     
  Complexity      473      473              
============================================
  Files           128      128              
  Lines          7779     7783       +4     
  Branches       1064     1064              
============================================
  Hits           2169     2169              
- Misses         5338     5342       +4     
  Partials        272      272              

Files	Coverage Δ
.../kotlin/org/jitsi/jicofo/rest/ConferenceRequest.kt	0.00% <ø> (ø)
...c/main/java/org/jitsi/jicofo/xmpp/BaseBrewery.java	0.00% <0.00%> (ø)
.../kotlin/org/jitsi/jicofo/conference/Participant.kt	52.76% <0.00%> (ø)
...n/kotlin/org/jitsi/jicofo/jibri/JibriSipGateway.kt	16.66% <0.00%> (ø)
...n/org/jitsi/jicofo/xmpp/AuthenticationIqHandler.kt	0.00% <0.00%> (ø)
...ain/kotlin/org/jitsi/jicofo/xmpp/JibriIqHandler.kt	0.00% <0.00%> (ø)
...in/kotlin/org/jitsi/jicofo/xmpp/JigasiIqHandler.kt	71.07% <75.00%> (ø)
...mmon/src/main/kotlin/org/jitsi/jicofo/xmpp/Util.kt	0.00% <0.00%> (ø)
...tlin/org/jitsi/jicofo/xmpp/jingle/JingleSession.kt	0.00% <0.00%> (ø)
...i/jicofo/conference/ParticipantInviteRunnable.java	50.63% <0.00%> (-0.33%)	⬇️
... and 10 more

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[JonathanLennox]

If your method in jitsi-xmpp-extensions were on Element rather than ExtensionElement this could just use the non-companion flavor of toStringOpt -- is it worth it? (I think it clearly would be if this were Kotlin, but it's less obvious for Java.)

[bgrozev]

I noticed this was awkward, but I didn't think it's worth another jitsi-xmpp-extensions update