Dubbo 2.6.x may not support multi group consumer #7985

[qixiaobo]

ref to #7985

Just add some default keys to avoid such special cases

[codecov-commenter]

Codecov Report

Merging #7997 (fb25c72) into 2.6.x (077da34) will decrease coverage by 0.04%.
The diff coverage is 33.33%.

@@             Coverage Diff              @@
##              2.6.x    #7997      +/-   ##
============================================
- Coverage     47.10%   47.06%   -0.05%     
+ Complexity     4463     4462       -1     
============================================
  Files           573      573              
  Lines         25575    25581       +6     
  Branches       4537     4539       +2     
============================================
- Hits          12048    12039       -9     
- Misses        11671    11686      +15     
  Partials       1856     1856              

Impacted Files	Coverage Δ
...libaba/dubbo/rpc/cluster/support/ClusterUtils.java	62.26% <33.33%> (-3.70%)	⬇️
...ba/dubbo/remoting/transport/netty/NettyClient.java	72.88% <0.00%> (-10.17%)	⬇️
...ubbo/rpc/protocol/dubbo/ChannelWrappedInvoker.java	37.50% <0.00%> (-4.17%)	⬇️
...dubbo/rpc/protocol/dubbo/CallbackServiceCodec.java	77.20% <0.00%> (-2.21%)	⬇️
.../dubbo/rpc/protocol/dubbo/filter/FutureFilter.java	54.54% <0.00%> (-2.03%)	⬇️
...libaba/dubbo/rpc/protocol/dubbo/DubboProtocol.java	58.33% <0.00%> (-0.88%)	⬇️
...java/com/alibaba/dubbo/config/ReferenceConfig.java	53.95% <0.00%> (+0.71%)	⬆️
...om/alibaba/dubbo/rpc/filter/ActiveLimitFilter.java	83.33% <0.00%> (+5.55%)	⬆️

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[chickenlj]

LGTM.