[SCB-2070]when main is default package(empty), start up will fail

[liubao68]

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[codecov-io]

Codecov Report

Merging #2112 (f4a1065) into master (9cc06e4) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master    #2112      +/-   ##
============================================
+ Coverage     80.85%   80.86%   +0.01%     
  Complexity     1335     1335              
============================================
  Files          1456     1456              
  Lines         39925    39925              
  Branches       3387     3387              
============================================
+ Hits          32281    32286       +5     
+ Misses         6176     6170       -6     
- Partials       1468     1469       +1     

Impacted Files	Coverage Δ	Complexity Δ
...servicecomb/foundation/common/utils/BeanUtils.java	91.83% <100.00%> (ø)	0.00 <0.00> (ø)
.../servicecomb/config/client/ConfigCenterClient.java	52.11% <0.00%> (-0.43%)	0.00% <0.00%> (ø%)
...egistry/client/http/ServiceRegistryClientImpl.java	70.09% <0.00%> (+0.77%)	0.00% <0.00%> (ø%)
...mb/serviceregistry/client/http/RestClientUtil.java	77.57% <0.00%> (+1.86%)	0.00% <0.00%> (ø%)

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