[ISSUE #2110] Support low version Zookeeper as registry center

[mytang0]

Fixes #2110 .

Changes proposed in this pull request:

• Support low version Zookeeper as registry center.

[codecov-commenter]

Codecov Report

Merging #2111 (6caa518) into master (8eac50a) will decrease coverage by 1.07%. The diff coverage is 71.25%.

@@             Coverage Diff              @@
##             master    #2111      +/-   ##
============================================
- Coverage     85.27%   84.19%   -1.08%     
+ Complexity     1893      231    -1662     
============================================
  Files           282      289       +7     
  Lines          6158     6645     +487     
  Branches        736      966     +230     
============================================
+ Hits           5251     5595     +344     
- Misses          566      695     +129     
- Partials        341      355      +14     

Impacted Files	Coverage Δ
...asticjob/reg/curator2/ZookeeperRegistryCenter.java	67.13% <67.13%> (ø)
...asticjob/reg/curator4/ZookeeperRegistryCenter.java	68.84% <68.84%> (ø)
...sticjob/reg/curator2/ZookeeperElectionService.java	85.18% <85.18%> (ø)
...sticjob/reg/curator4/ZookeeperElectionService.java	85.18% <85.18%> (ø)
...he/curator/framework/listen/ListenerContainer.java	100.00% <100.00%> (ø)
...tion/ZookeeperCuratorIgnoredExceptionProvider.java	100.00% <100.00%> (ø)
...tion/ZookeeperCuratorIgnoredExceptionProvider.java	100.00% <100.00%> (ø)
...re/elasticjob/lite/internal/server/ServerNode.java	80.00% <0.00%> (-20.00%)	:arrow_down:
...ite/internal/election/ElectionListenerManager.java	96.00% <0.00%> (-4.00%)	:arrow_down:
...here/elasticjob/http/executor/HttpJobExecutor.java	92.30% <0.00%> (ø)

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[TeslaCN]

Hi @mytang0 Thanks for your contribution. Actually I want to discuss about reusing ShardingSphere's cluster mode in ElasticJob. Maintaining similar codes in sub-project will disperse developers' energies. You may start a discussion about supporting legacy version Curator in ShardingSphere Cluster mode. What do you think?

[mytang0]

Hi @mytang0 Thanks for your contribution. Actually I want to discuss about reusing ShardingSphere's cluster mode in ElasticJob. Maintaining similar codes in sub-project will disperse developers' energies. You may start a discussion about supporting legacy version Curator in ShardingSphere Cluster mode. What do you think?

Ok.

[SuperCarrys]

There is no standardized result before this problem target, such as how the low version of zk uses the 3.x version of elasticjob