Fix: now properly removing dangling default links

[quintesse]

The links for global default and version default JDKs weren't properly removed, confusing older JBang versions.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: f2133d09-59af-4114-8d3f-413036291010

📥 Commits

Reviewing files that changed from the base of the PR and between a7fdea8 and 9f30c12.

📒 Files selected for processing (3)

• src/main/java/dev/jbang/devkitman/JdkManager.java
• src/main/java/dev/jbang/devkitman/util/FileUtils.java
• src/test/java/dev/jbang/devkitman/TestJdkManager.java

---

📝 Walkthrough

Walkthrough

This PR refactors JDK uninstall handling to use nullable object references for tracking default state instead of boolean flags, adds robust file-identity comparison with fallback logic, corrects versioned-default detection, implements Windows directory junction support in FileUtils, and extends test coverage to validate default replacement selection and link removal.

Changes

JDK Uninstall Default State Handling

Layer / File(s)	Summary
Default state detection and reset logic src/main/java/dev/jbang/devkitman/JdkManager.java	uninstallJdk replaces boolean reset flags with nullable Jdk.InstalledJdk references (resetDefault, resetDefaultVer), uses Files.isSameFile (with IOException fallback to equals) to detect matching defaults, fixes versioned-default lookup to getDefaultJdkForVersion(jdk.majorVersion()), and conditionally replaces detected defaults with next/prev installed JDK or unsets via direct uninstall() call when no replacement exists.
Windows directory link creation src/main/java/dev/jbang/devkitman/util/FileUtils.java	createLink detects directory targets on Windows and creates them as junctions with logging; non-directory and non-Windows paths fall back to symbolic link creation.
Test coverage for default uninstall and link verification src/test/java/dev/jbang/devkitman/TestJdkManager.java	Test suite adds coverage for getDefaultJdkForVersion in default and default-plus scenarios, expands uninstall tests to verify pre-uninstall per-version defaults, assert replacement selection after uninstalling global/versioned defaults, and verify uninstalled JDK homes/links no longer exist via Files.exists with NOFOLLOW_LINKS.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 A JDK falls, but all is not lost,
With nullables tracking the default's cost,
Windows gets junctions where symlinks won't dance,
Tests verify each link's last chance. 🔗✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: fixing the removal of dangling default links, which is the primary objective addressed across the JdkManager refactoring and test expansions.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix_102

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}