fix checkstyle: delete unused import by seagle-yuan · Pull Request #1874 · apache/hugegraph

@@             Coverage Diff              @@
##             master    #1874      +/-   ##
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+ Coverage     66.92%   70.97%   +4.05%     
  Complexity      980      980              
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  Files           447      447              
  Lines         38096    38096              
  Branches       5404     5404              
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+ Hits          25494    27037    +1543     
+ Misses        10086     8413    -1673     
- Partials       2516     2646     +130