[ISSUE #261]Modify the configure of ObjectMapper

[ni-ze]

1. change operator name of groupedstream;
2. modify the configure of ObjectMapper;

close #261

[codecov-commenter]

Codecov Report

Merging #260 (2906e9b) into develop (51d13d5) will not change coverage.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           develop    #260   +/-   ##
=======================================
  Coverage     0.00%   0.00%           
=======================================
  Files           79      79           
  Lines         2646    2665   +19     
  Branches       252     252           
=======================================
- Misses        2646    2665   +19     

Impacted Files	Coverage Δ
...cketmq/streams/core/rstream/GroupedStreamImpl.java	0.00% <0.00%> (ø)
...he/rocketmq/streams/core/running/WorkerThread.java	0.00% <0.00%> (ø)
.../core/serialization/deImpl/KVJsonDeserializer.java	0.00% <0.00%> (ø)
...s/core/serialization/serImpl/KVJsonSerializer.java	0.00% <0.00%> (ø)
.../rocketmq/streams/core/util/OperatorNameMaker.java	0.00% <ø> (ø)
...a/org/apache/rocketmq/streams/core/util/Utils.java	0.00% <0.00%> (ø)

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