fix bug about nacos

[IanCao]

What is the purpose of the change

XXXXX

Brief changelog

XXXXX

Verifying this change

XXXXX

Follow this checklist to help us incorporate your contribution quickly and easily:

• Make sure there is a GITHUB_issue field for the change (usually before you start working on it). Trivial changes like typos do not require a GITHUB issue. Your pull request should address just this issue, without pulling in other changes - one PR resolves one issue.
• Format the pull request title like [Dubbo-XXX] Fix UnknownException when host config not exist #XXX. Each commit in the pull request should have a meaningful subject line and body.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit-test to verify your logic correction, more mock a little better when cross module dependency exist. If the new feature or significant change is committed, please remember to add sample in dubbo samples project.
• Run mvn clean install -DskipTests=false & mvn clean test-compile failsafe:integration-test to make sure unit-test and integration-test pass.
• If this contribution is large, please follow the Software Donation Guide.

[IanCao]

alibaba/nacos#1364

[codecov-io]

Codecov Report

Merging #4308 into master will decrease coverage by 0.01%.
The diff coverage is 0%.

@@             Coverage Diff              @@
##             master    #4308      +/-   ##
============================================
- Coverage     62.88%   62.86%   -0.02%     
+ Complexity      506      503       -3     
============================================
  Files           769      769              
  Lines         32995    32995              
  Branches       5215     5215              
============================================
- Hits          20749    20743       -6     
- Misses         9844     9847       +3     
- Partials       2402     2405       +3

Impacted Files	Coverage Δ	Complexity Δ
...che/dubbo/registry/nacos/NacosRegistryFactory.java	0% <0%> (ø)	0 <0> (ø)	⬇️
.../remoting/transport/netty4/NettyServerHandler.java	61.9% <0%> (-9.53%)	0% <0%> (ø)
.../apache/dubbo/remoting/transport/AbstractPeer.java	58.69% <0%> (-8.7%)	0% <0%> (ø)
...e/dubbo/remoting/transport/netty/NettyChannel.java	57.64% <0%> (-4.71%)	20% <0%> (-1%)
...ache/dubbo/registry/multiple/MultipleRegistry.java	62.67% <0%> (-1.41%)	20% <0%> (-2%)
...pache/dubbo/registry/support/AbstractRegistry.java	81.6% <0%> (+1.53%)	0% <0%> (ø)	⬇️
...he/dubbo/registry/multicast/MulticastRegistry.java	69.68% <0%> (+1.8%)	0% <0%> (ø)	⬇️

---

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 6f3a05c...16bd49e. Read the comment docs.

[andyqian]

sorry

[andyqian]

Thank you for your contribution

[kezhenxu94]

LGTM. Thanks for contributing

[htynkn]

Use StringUtils in nacos client is not right, but I still it's good to use util in dubbo common, refer to

dubbo/dubbo-common/src/main/java/org/apache/dubbo/common/utils/StringUtils.java

Line 356 in fe3d345

public static boolean isEmpty(String str) {

Or util in org.apache.commons.lang3

[ralf0131]

LGTM.