Fix BUG: The generic filter and default reference filters lack ','

[flycash]

What this PR does:
The lack of ',' between generic filter and default reference filters
Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[codecov-io]

Codecov Report

Merging #260 into develop will decrease coverage by 0.55%.
The diff coverage is 0%.

@@             Coverage Diff             @@
##           develop     #260      +/-   ##
===========================================
- Coverage    66.17%   65.62%   -0.56%     
===========================================
  Files          111      111              
  Lines         7042     7042              
===========================================
- Hits          4660     4621      -39     
- Misses        1923     1964      +41     
+ Partials       459      457       -2

Impacted Files	Coverage Δ
config/reference_config.go	80.89% <0%> (ø)	⬆️
protocol/dubbo/pool.go	57.86% <0%> (-15.74%)	⬇️
protocol/dubbo/listener.go	51.19% <0%> (-10.72%)	⬇️
protocol/dubbo/codec.go	76.47% <0%> (-5.89%)	⬇️
protocol/dubbo/readwriter.go	67.9% <0%> (-2.47%)	⬇️
cluster/cluster_impl/failback_cluster_invoker.go	78.49% <0%> (-2.16%)	⬇️
remoting/zookeeper/client.go	64.45% <0%> (+0.57%)	⬆️
registry/etcdv3/registry.go	51.51% <0%> (+1.01%)	⬆️
remoting/zookeeper/listener.go	47.93% <0%> (+1.03%)	⬆️
config_center/zookeeper/listener.go	86.95% <0%> (+4.34%)	⬆️
... and 1 more

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[fangyincheng]

LGTM