[ISSUE #5830] fix bug in GetMessageResult#getMessageCount

[ShadowySpirits]

fix #5830

[codecov-commenter]

Codecov Report

Merging #5831 (397c23a) into develop (9b3b551) will decrease coverage by 0.03%.
The diff coverage is 100.00%.

@@              Coverage Diff              @@
##             develop    #5831      +/-   ##
=============================================
- Coverage      42.45%   42.42%   -0.04%     
  Complexity      8230     8230              
=============================================
  Files           1060     1060              
  Lines          73414    73416       +2     
  Branches        9606     9606              
=============================================
- Hits           31171    31148      -23     
- Misses         38319    38345      +26     
+ Partials        3924     3923       -1     

Impacted Files	Coverage Δ
...va/org/apache/rocketmq/store/GetMessageResult.java	87.67% <100.00%> (+10.20%)	⬆️
...controller/impl/DefaultBrokerHeartbeatManager.java	82.27% <0.00%> (-3.80%)	⬇️
...a/org/apache/rocketmq/broker/BrokerController.java	43.29% <0.00%> (-3.43%)	⬇️
...he/rocketmq/client/trace/AsyncTraceDispatcher.java	82.21% <0.00%> (-2.41%)	⬇️
...ache/rocketmq/proxy/common/ReceiptHandleGroup.java	65.30% <0.00%> (-2.05%)	⬇️
...he/rocketmq/broker/processor/PopReviveService.java	39.62% <0.00%> (-1.35%)	⬇️
...a/org/apache/rocketmq/store/StoreStatsService.java	33.97% <0.00%> (-1.11%)	⬇️
...che/rocketmq/acl/plain/PlainPermissionManager.java	78.22% <0.00%> (-0.54%)	⬇️
...ava/org/apache/rocketmq/store/MappedFileQueue.java	62.25% <0.00%> (-0.50%)	⬇️
...mq/client/impl/producer/DefaultMQProducerImpl.java	46.17% <0.00%> (-0.25%)	⬇️
... and 12 more

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[lollipopjin]

LGTM