[SCB-2673]Fix NPE problem when auto discovery enabled

[liubao68]

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[codecov-commenter]

Codecov Report

Merging #3299 (8a11849) into master (6677331) will increase coverage by 0.00%.
The diff coverage is 67.69%.

❗ Current head 8a11849 differs from pull request most recent head 9e26f48. Consider uploading reports for the commit 9e26f48 to get more accurate results

@@            Coverage Diff            @@
##             master    #3299   +/-   ##
=========================================
  Coverage     77.41%   77.41%           
- Complexity     1449     1452    +3     
=========================================
  Files          1649     1650    +1     
  Lines         43721    43740   +19     
  Branches       3674     3676    +2     
=========================================
+ Hits          33847    33862   +15     
- Misses         8347     8350    +3     
- Partials       1527     1528    +1     

Impacted Files	Coverage Δ
...nfig/center/client/ConfigCenterAddressManager.java	100.00% <ø> (ø)
...ecomb/config/center/client/ConfigCenterClient.java	0.00% <0.00%> (ø)
...ice/center/client/ServiceCenterAddressManager.java	71.42% <ø> (ø)
...omb/service/center/client/ServiceCenterClient.java	24.30% <ø> (ø)
...comb/service/center/client/ServiceCenterWatch.java	0.00% <ø> (ø)
...mb/config/ConfigCenterConfigurationSourceImpl.java	10.63% <0.00%> (+1.06%)	⬆️
...omb/serviceregistry/auth/RBACBootStrapService.java	8.53% <0.00%> (ø)
...omb/http/client/common/AbstractAddressManager.java	75.55% <69.56%> (-5.40%)	⬇️
...comb/demo/springmvc/client/TestControllerImpl.java	80.00% <80.00%> (ø)
.../service/center/client/ServiceCenterRawClient.java	65.00% <100.00%> (ø)
... and 7 more

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