Relax Checkstyle MethodName for test sources

383 of the 399 MethodName warnings are JUnit tests using the widely-adopted methodName_describesScenario convention, e.g.

• findPropertyName_readsSerializedNameOnField
• findPropertyName_ignoresAnnotationOnGetter
• findPropertyName_returnsNullWhenUnannotated

The default Checkstyle pattern ^[a-z][a-zA-Z0-9]*$ rejects underscores. Renaming 383 tests would lose readable scenario labels for no benefit.

Proposed fix

Configure a separate, more permissive MethodName pattern for test sources. Simplest path is per-task configFile in the root build.gradle.kts:

```kotlin
tasks.named("checkstyleTest") {
configFile = rootProject.file("config/checkstyle/checkstyle-test.xml")
}
```

with checkstyle-test.xml overriding only MethodName:

```xml



```

This drops the count from 399 to 16 (the production offenders tracked in the rename issue) and means the test-naming convention is allowed by policy, not just by neglect.

Start in the root build.gradle.kts and inspect the existing Checkstyle configuration, then compare it with the test sources and config/checkstyle/checkstyle-test.xml. Run the checkstyleTest task and verify that the test naming convention is accepted while the remaining production MethodName warnings stay reported.