readability enhancement and assert check for proxy object #3032

[khanimteyaz]

What is the purpose of the change

Assert check for proxy object and readbility enhancement for
1.ConsumerModel.java
2.InvokeTelnetHandler.java
3.ListTelnetHandler.java

Brief changelog

Assert check and readbility enhancement for
1.ConsumerModel.java
2.InvokeTelnetHandler.java
3.ListTelnetHandler.java

Verifying this change

Running UT

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

• Make sure there is a [GITHUB_issue] (Readability enhancementfor telnate related changes #3032) 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 integration-test in test module.
• 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.

[codecov-io]

Codecov Report

Merging #3048 into master will decrease coverage by <.01%.
The diff coverage is 69.56%.

@@            Coverage Diff             @@
##           master    #3048      +/-   ##
==========================================
- Coverage   64.37%   64.37%   -0.01%     
==========================================
  Files         584      584              
  Lines       26085    26096      +11     
  Branches     4559     4559              
==========================================
+ Hits        16793    16800       +7     
- Misses       7115     7122       +7     
+ Partials     2177     2174       -3

Impacted Files	Coverage Δ
...rpc/protocol/dubbo/telnet/InvokeTelnetHandler.java	74.16% <100%> (+2.37%)	⬆️
...ain/java/org/apache/dubbo/common/utils/Assert.java	81.81% <100%> (+6.81%)	⬆️
...java/org/apache/dubbo/rpc/model/ConsumerModel.java	73.68% <100%> (+11.18%)	⬆️
...o/rpc/protocol/dubbo/telnet/ListTelnetHandler.java	65.78% <22.22%> (-0.43%)	⬇️
...che/dubbo/remoting/transport/mina/MinaChannel.java	43.42% <0%> (-10.53%)	⬇️
...ava/org/apache/dubbo/config/DubboShutdownHook.java	78.12% <0%> (-6.25%)	⬇️
...onfig/spring/extension/SpringExtensionFactory.java	80.48% <0%> (-4.88%)	⬇️
...pache/dubbo/registry/support/AbstractRegistry.java	80.07% <0%> (-1.88%)	⬇️
...he/dubbo/registry/multicast/MulticastRegistry.java	63.79% <0%> (-1.73%)	⬇️
.../java/org/apache/dubbo/config/ReferenceConfig.java	56.01% <0%> (-0.38%)	⬇️
... and 6 more

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[beiwei30]

LGTM.

[khanimteyaz]

LGTM.

Thanks for reviewing it.