[SCB-2318]revert PR[#2350] and add test case for map null value

[liubao68]

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[codecov-commenter]

Codecov Report

Merging #2580 (503981a) into master (fff8c3e) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##             master    #2580   +/-   ##
=========================================
  Coverage     77.67%   77.68%           
  Complexity     1427     1427           
=========================================
  Files          1598     1598           
  Lines         42574    42576    +2     
  Branches       3588     3585    -3     
=========================================
+ Hits          33071    33074    +3     
+ Misses         8003     8001    -2     
- Partials       1500     1501    +1     

Impacted Files	Coverage Δ
...pache/servicecomb/demo/pojo/client/PojoClient.java	82.60% <ø> (-0.28%)	⬇️
...vicecomb/demo/pojo/client/CodeFirstPojoClient.java	97.77% <100.00%> (+0.34%)	⬆️
...n/java/org/apache/servicecomb/AuthHandlerBoot.java	100.00% <100.00%> (+20.00%)	⬆️
...icecomb/authentication/RSAAuthenticationToken.java	100.00% <100.00%> (+6.45%)	⬆️
...thentication/provider/RSAProviderTokenManager.java	78.37% <100.00%> (+5.65%)	⬆️
...ervicecomb/foundation/vertx/stream/PumpCommon.java	70.37% <0.00%> (-7.41%)	⬇️
...b/core/invocation/timeout/PassingTimeStrategy.java	94.44% <0.00%> (-5.56%)	⬇️
.../servicecomb/registry/discovery/DiscoveryTree.java	96.49% <0.00%> (-3.51%)	⬇️
...cecomb/registry/consumer/MicroserviceVersions.java	87.39% <0.00%> (-1.69%)	⬇️
...egistry/client/http/ServiceRegistryClientImpl.java	70.88% <0.00%> (-0.39%)	⬇️
... and 1 more

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