[feat][client] Support forward proxy for the ZTS server in pulsar-client-auth-athenz

[equanz]

Motivation

When we can only access the Athenz ZTS server through a forward proxy, we can't use pulsar-client-auth-athenz for an authentication plugin because the current plugin implementation does not support the ztsProxyUrl config of ZTSClient.

Modifications

Support ztsProxyUrl in the pulsar-client-auth-athenz.

Verifying this change

• Make sure that the change passes the CI checks.

This change added tests and can be verified as follows:

• Added an unit test for ztsProxyUrl config

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository: equanz#12

[lhotari]

LGTM

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 74.23%. Comparing base (bbc6224) to head (5a56563).
Report is 886 commits behind head on master.

Files with missing lines	Patch %	Lines
.../pulsar/client/impl/auth/AuthenticationAthenz.java	80.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #23947      +/-   ##
============================================
+ Coverage     73.57%   74.23%   +0.65%     
+ Complexity    32624    31877     -747     
============================================
  Files          1877     1853      -24     
  Lines        139502   143743    +4241     
  Branches      15299    16337    +1038     
============================================
+ Hits         102638   106705    +4067     
+ Misses        28908    28621     -287     
- Partials       7956     8417     +461     

Flag	Coverage Δ
inttests	26.65% <ø> (+2.07%)	⬆️
systests	23.24% <ø> (-1.08%)	⬇️
unittests	73.74% <80.00%> (+0.90%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
.../pulsar/client/impl/auth/AuthenticationAthenz.java	64.03% <80.00%> (+4.57%)	⬆️

... and 1036 files with indirect coverage changes