rm incubating word

[Leishunyu]

What is the purpose of the change

#4108

Brief changelog

XXXXX

Verifying this change

XXXXX

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[codecov-io]

Codecov Report

Merging #4110 into master will increase coverage by 0.09%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #4110      +/-   ##
============================================
+ Coverage     62.57%   62.67%   +0.09%     
- Complexity      543      544       +1     
============================================
  Files           762      762              
  Lines         32752    32752              
  Branches       5162     5162              
============================================
+ Hits          20496    20528      +32     
+ Misses         9896     9863      -33     
- Partials       2360     2361       +1

Impacted Files	Coverage Δ	Complexity Δ
.../java/org/apache/dubbo/config/ReferenceConfig.java	59.7% <0%> (+0.36%)	0% <0%> (ø)	⬇️
...exchange/support/header/HeaderExchangeHandler.java	62.2% <0%> (+2.36%)	0% <0%> (ø)	⬇️
...pache/dubbo/registry/support/AbstractRegistry.java	81.6% <0%> (+3.06%)	0% <0%> (ø)	⬇️
.../org/apache/dubbo/remoting/ExecutionException.java	21.05% <0%> (+5.26%)	0% <0%> (ø)	⬇️
...ng/transport/dispatcher/all/AllChannelHandler.java	57.14% <0%> (+5.71%)	0% <0%> (ø)	⬇️
.../remoting/transport/netty4/NettyServerHandler.java	71.42% <0%> (+9.52%)	0% <0%> (ø)	⬇️
...che/dubbo/remoting/transport/mina/MinaChannel.java	53.94% <0%> (+10.52%)	17% <0%> (+1%)	⬆️
...ache/dubbo/remoting/p2p/support/AbstractGroup.java	56.81% <0%> (+11.36%)	0% <0%> (ø)	⬇️

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[ralf0131]

LGTM.

[lovepoem]

LGTM