Remove the never-public org.metricshub.winrm.backend property (#121)

[anuragpaul602-netizen]

Closes #121.

The property was a transitional guard around the CXF removal during 2.0.0 development — it defaulted to light and rejected cxf. No public release ever exposed it, so no user can have it set and the branches it guards are dead.

Code

• WinRMExecutorFactory — removed the public BACKEND_PROPERTY constant and the LIGHT / CXF constants; createInstance(...) now delegates straight to LightWinRMService.createInstance(...). The class and method Javadoc no longer mention the property, and the java.util.Locale import went with the toLowerCase call.
• WinRMExecutorFactoryTest — removed cxfBackendRejectedWithRemovalMessage, unsupportedBackendValueRejected, the @AfterEach that cleared the property, and every System.setProperty(...) call. With the property gone, lightBackendSelectedForHttpNtlm / defaultBackendIsLight and lightBackendAcceptsHttps / defaultBackendAcceptsHttps became identical pairs, so each pair is merged into a single test (createsLightExecutorOverHttp, createsLightExecutorOverHttps), keeping the stronger assertions. The capability guards — Kerberos-only over HTTP rejected, mixed Kerberos/NTLM fallback, Kerberos over HTTPS, closed-executor rejection — are untouched. 10 tests → 6.

Documentation

The issue notes the doc references were already removed, but three were still present, so they are removed here as well:

• src/site/markdown/index.md — this one sits under src/, which the acceptance criterion ("no reference anywhere in src/") covers.
• README.md — the upgrade note dropped from "Two consequences" to one.
• CHANGELOG.md — the bullet told readers to unset a property that will not exist in the release the entry describes.

Verification

• grep -rn "winrm.backend" src → nothing; repo-wide grep for winrm.backend and BACKEND_PROPERTY → nothing.
• createInstance(...) still returns a LightWinRMService, asserted by assertInstanceOf in the surviving tests.
• Checkstyle: 0. PMD: unchanged from main (91, none in the touched files — those are Fix the 89 PMD violations reported by the Maven site #122's business, and the two PRs do not overlap).
• mvn verify: 78 tests, all passing except WinRmCliTest.decodesCommandOutputUsingTheRemoteWindowsCodePage and WinRMWqlExecutorTest.testExecute, which fail identically on unmodified main here — Mockito's inline mock maker cannot mock under JDK 25. Unrelated to this change.

Branched from main and independent of #122, so the two can merge in either order.

[anuragpaul602-netizen]

I want to work further in this project. Can you add me as a contributor?

[bertysentry]

Thanks! Your two merged PRs already make you a contributor 😊 and you’re welcome to continue contributing through fork-based pull requests. We don’t grant repository write access based on initial contributions. For now, please agree on an issue with us before starting, keep one focused PR active at a time, disclose substantial AI assistance, and be prepared to explain and maintain every change. We can reconsider additional permissions after a sustained track record.