fix empty protocol for nacos. #4294.

[cvictory]

#4294

Nacos empty protocol

[codecov-io]

Codecov Report

Merging #4349 into master will decrease coverage by 0.06%.
The diff coverage is 0%.

@@             Coverage Diff              @@
##             master    #4349      +/-   ##
============================================
- Coverage     62.92%   62.85%   -0.07%     
+ Complexity      505      504       -1     
============================================
  Files           769      769              
  Lines         32995    33004       +9     
  Branches       5215     5216       +1     
============================================
- Hits          20762    20745      -17     
- Misses         9837     9858      +21     
- Partials       2396     2401       +5

Impacted Files	Coverage Δ	Complexity Δ
...org/apache/dubbo/registry/nacos/NacosRegistry.java	0% <0%> (ø)	0 <0> (ø)	⬇️
...e/dubbo/remoting/transport/netty/NettyChannel.java	57.64% <0%> (-4.71%)	20% <0%> (-1%)
...c/main/java/org/apache/dubbo/rpc/RpcException.java	82.75% <0%> (-3.45%)	0% <0%> (ø)
...bo/rpc/cluster/support/FailbackClusterInvoker.java	67.21% <0%> (-3.28%)	0% <0%> (ø)
...pache/dubbo/registry/support/AbstractRegistry.java	78.54% <0%> (-3.07%)	0% <0%> (ø)
.../apache/dubbo/remoting/transport/AbstractPeer.java	71.73% <0%> (-2.18%)	0% <0%> (ø)
...he/dubbo/registry/multicast/MulticastRegistry.java	67.87% <0%> (-1.81%)	0% <0%> (ø)
...pache/dubbo/remoting/transport/AbstractServer.java	47.91% <0%> (-1.05%)	0% <0%> (ø)
...ache/dubbo/registry/multiple/MultipleRegistry.java	62.67% <0%> (-0.71%)	20% <0%> (-1%)
...che/dubbo/remoting/transport/mina/MinaChannel.java	55.26% <0%> (+1.31%)	18% <0%> (+1%)	⬆️
... and 1 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 041a6ad...f784352. Read the comment docs.