Stabilize MethodConfigTest by disabling metrics initialization to avoid Micrometer nondeterminism

[Anshul-creator]

What is the purpose of the change?

This PR stabilizes the following tests in MethodConfigTest:

• testOverrideMethodConfigOfService
• testAddMethodConfigOfService
• testOverrideMethodConfigOfReference
• testAddMethodConfigOfReference
• testIgnoreInvalidMethodConfigOfService

These tests were intermittently failing under randomized execution orders (NonDex) due to nondeterministic behavior in Micrometer’s composite meter registry. The tests focus on method-level configuration overrides and do not intend to validate metrics behavior. Yet, the metrics subsystem was being initialized as part of the bootstrap process, introducing unnecessary nondeterminism.

Root Cause

During application bootstrap, Dubbo initializes the metrics subsystem, which in turn configures Micrometer’s composite meter registry. Internally, Micrometer uses an IdentityHashMap whose iteration behavior is not deterministic under randomized JVM execution orders.

Under certain NonDex seeds, this produces:

java.lang.ArrayIndexOutOfBoundsException
  at java.util.IdentityHashMap$KeyIterator.next(...)
  at io.micrometer.core.instrument.composite.CompositeMeterRegistry.updateDescendants(...)

These failures occur before the tests exercise any method-configuration logic, so the flakiness is caused purely by nondeterministic metrics initialization and not by the MethodConfig functionality under test.

Changes Made

• Added test-local configuration to explicitly disable the metrics subsystem for every test in MethodConfigTest.
• Ensured isolation by calling SysProps.clear() in @BeforeEach and DubboBootstrap.reset() in @AfterEach, so no metrics/config-related state leaks across tests.
• Kept all existing assertions and behavior intact.

Verification

You can try running the following snippet of code from the dubbo repo root, on both pre-fix and post-fix code

./mvnw -q -pl dubbo-config/dubbo-config-api \
  edu.illinois:nondex-maven-plugin:2.2.1:nondex \
  -DnondexRuns=20

The tests should fail intermittently on the pre-fix version, but pass consistently across all seeds on the post-fix version.
NonDex run logs will be available under the dubbo-config/dubbo-config-api/.nondex directory.

Checklist

• Make sure there is a GitHub_issue field for the change.
• 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. If the new feature or significant change is committed, please remember to add sample in dubbo samples project.
• Make sure gitHub actions can pass. Why the workflow is failing and how to fix it?

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.67%. Comparing base (58d7386) to head (771fe6e).

Additional details and impacted files

@@             Coverage Diff              @@
##                3.3   #15782      +/-   ##
============================================
- Coverage     60.77%   59.67%   -1.10%     
+ Complexity    11706    11685      -21     
============================================
  Files          1938     1938              
  Lines         88646    88643       -3     
  Branches      13379    13379              
============================================
- Hits          53875    52899     -976     
- Misses        29249    30291    +1042     
+ Partials       5522     5453      -69     

Flag	Coverage Δ
integration-tests-java21	32.45% <ø> (+0.09%)	⬆️
integration-tests-java8	32.49% <ø> (+0.05%)	⬆️
samples-tests-java21	32.10% <ø> (+0.12%)	⬆️
samples-tests-java8	29.72% <ø> (-0.02%)	⬇️
unit-tests-java11	?
unit-tests-java17	?
unit-tests-java21	?
unit-tests-java25	?
unit-tests-java8	59.08% <ø> (ø)

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[songxiaosheng]

LGTM

[zrlw]

LGTM