refactor: Refactoring the Result Class

[YongGoose]

• I have registered the PR changes.

Ⅰ. Describe what this PR did

Ⅱ. Does this pull request fix one issue?

fixes #7158

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov]

Codecov Report

Attention: Patch coverage is 41.50943% with 31 lines in your changes missing coverage. Please review.

Project coverage is 52.13%. Comparing base (679a2e0) to head (c8d355a).
Report is 2 commits behind head on 2.x.

Files with missing lines	Patch %	Lines
...ache/seata/namingserver/manager/NamingManager.java	12.50%	14 Missing ⚠️
...eata/namingserver/controller/NamingController.java	30.00%	7 Missing ⚠️
...ata/server/controller/VGroupMappingController.java	0.00%	4 Missing ⚠️
...seata/server/console/impl/AbstractLockService.java	0.00%	2 Missing ⚠️
...che/seata/server/controller/ClusterController.java	0.00%	2 Missing ⚠️
...in/java/org/apache/seata/common/result/Result.java	50.00%	1 Missing ⚠️
...eata/namingserver/controller/HealthController.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x    #7176      +/-   ##
============================================
- Coverage     52.20%   52.13%   -0.07%     
- Complexity     6817     6864      +47     
============================================
  Files          1154     1169      +15     
  Lines         41116    41429     +313     
  Branches       4820     4848      +28     
============================================
+ Hits          21464    21601     +137     
- Misses        17611    17775     +164     
- Partials       2041     2053      +12     

Files with missing lines	Coverage Δ
...main/java/org/apache/seata/common/result/Code.java	89.47% <100.00%> (ø)
...ava/org/apache/seata/common/result/PageResult.java	87.71% <100.00%> (ø)
...a/org/apache/seata/common/result/SingleResult.java	100.00% <100.00%> (+15.38%)	⬆️
...in/java/org/apache/seata/common/result/Result.java	77.77% <50.00%> (+24.44%)	⬆️
...eata/namingserver/controller/HealthController.java	50.00% <0.00%> (ø)
...seata/server/console/impl/AbstractLockService.java	9.09% <0.00%> (ø)
...che/seata/server/controller/ClusterController.java	8.88% <0.00%> (+0.19%)	⬆️
...ata/server/controller/VGroupMappingController.java	11.76% <0.00%> (+2.24%)	⬆️
...eata/namingserver/controller/NamingController.java	28.57% <30.00%> (-10.32%)	⬇️
...ache/seata/namingserver/manager/NamingManager.java	49.39% <12.50%> (-6.57%)	⬇️

... and 15 files with indirect coverage changes

[slievrly]

An implicit success isn't a great design choice because it doesn't align with the conventional understanding of a zero value. If it needs to represent success, it's better to make it clear in the method name rather than assigning it to a default constructor.

[YongGoose]

Good catch :)
Done in 3b4370f !

[YongGoose]

One of the refactorings I made was distinguishing between setting the message of Result as a String and making the generic type of Result a String—these are separate concerns.

• https://docs.oracle.com/javase/tutorial/java/generics/types.html

I understand that there are many instances of this pattern in the code.
I plan to focus on refactoring this part as well.