Don't warn when JDK path from env var is not a directory

[Copilot]

When JI_JAVA_HOME (or other JDK path sources) points to a path that exists but is not a directory (e.g., a file or broken symlink), TryGetJdkInfo was propagating the ArgumentException from JdkInfo..ctor as a TraceLevel.Warning, producing noisy, misleading output in MSBuild logs.

Changes

• JdkInfo.TryGetJdkInfo: Add an early Directory.Exists guard. Paths that don't resolve to a directory are now silently skipped — logged only at Verbose — rather than emitting a Warning.

// Before: ArgumentException from ctor was caught and logged as Warning
internal static JdkInfo? TryGetJdkInfo(string path, ...)
{
    try { jdk = new JdkInfo(path, locator); }
    catch (Exception e) {
        logger(TraceLevel.Warning, ...);  // ← showed up in MSBuild output
    }
}

// After: non-directory paths are skipped before construction
if (!Directory.Exists(path)) {
    logger(TraceLevel.Verbose, $"Skipping JDK path `{path}`...");
    return null;
}

• New test GetKnownSystemJdkInfos_JiJavaHome_NonDirectoryPath_NoWarning: sets JI_JAVA_HOME to a temp file path and asserts no Warning is logged.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>ArgumentException looking for JDKs</issue_title>
<issue_description>This happened in a test here:

• https://devdiv.visualstudio.com/DevDiv/_build/results?buildId=5751716&view=ms.vss-test-web.build-test-results-tab&runId=33356848&resultId=100155&paneView=attachments
• Seems unrelated to the changes: [Xamarin.Android.Build.Tasks] update built-in .aotprofile's android#6745

23:21:22.063   1:7>/Users/runner/android-toolchain/dotnet/packs/Microsoft.Android.Sdk.Darwin/31.0.200-ci.pr.gh6745.77/tools/Xamarin.Android.Tooling.targets(69,5): warning : An exception occurred while validating the Java SDK installation in '/Users/runner/Library/Android/jdk-11' that was found while searching the paths from '$JI_JAVA_HOME'. Ensure that the Android section of the Visual Studio options has a valid Java SDK directory configured. To use a custom SDK path for a command line build, set the 'JavaSdkDirectory' MSBuild property to the custom path. Exception: Not a directory (Parameter 'homePath') [/Users/runner/work/1/a/TestRelease/02-14_22.59.11/temp/NothingToBindclass-parse/UnnamedProject.csproj]
                     System.ArgumentException: Not a directory (Parameter 'homePath')
                        at Xamarin.Android.Tools.JdkInfo..ctor(String homePath, String locator, Action`2 logger) in /Users/builder/azdo/_work/2/s/xamarin-android/external/xamarin-android-tools/src/Xamarin.Android.Tools.AndroidSdk/JdkInfo.cs:line 57
                        at Xamarin.Android.Tools.JdkInfo..ctor(String homePath, String locator) in /Users/builder/azdo/_work/2/s/xamarin-android/external/xamarin-android-tools/src/Xamarin.Android.Tools.AndroidSdk/JdkInfo.cs:line 97
                        at Xamarin.Android.Tools.JdkInfo.TryGetJdkInfo(String path, Action`2 logger, String locator) in /Users/builder/azdo/_work/2/s/xamarin-android/external/xamarin-android-tools/src/Xamarin.Android.Tools.AndroidSdk/JdkInfo.cs:line 347 (TaskId:57)

The MSBuild log says $JI_JAVA_HOME is:

JI_JAVA_HOME = /Users/runner/Library/Android/jdk-11
```</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes ArgumentException looking for JDKs #154

---

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[kayodebristol]

@copilot This JDK warning fix is ready! ✅

Status: CI passing, mergeable=true
Ready for: Immediate review and merge

This appears to be a clean, focused fix for the JDK path warning issue. Consider:

1. Converting from draft to ready for review
2. This looks ready for merge given its focused scope

Action needed: Mark ready for review - this one looks good to go!

[jonathanpeppers]

🤖 AI Review Summary

Found 1 issue: placeholder issue link in test comment.

• Documentation: Test comment references issues/XXX instead of the actual issue number #154 (JdkInfoTests.cs:315)

👍 What's good:

• Clean, minimal fix — the Directory.Exists guard is the right approach, preventing the misleading Warning from JdkInfo..ctor's ArgumentException.
• Logging at TraceLevel.Verbose instead of silently swallowing is good practice.
• Test properly creates a real temp file (not just a non-existent path), which reproduces the exact broken-symlink/file scenario from the original issue.
• Test correctly restores the JI_JAVA_HOME env var and cleans up the temp file in a finally block.

---

Review generated by android-tools-reviewer from review guidelines by @jonathanpeppers.

[jonathanpeppers]

🤖 Documentation — This references issues/XXX but should link to the actual issue #154 that this PR fixes.

Rule: Docs describe intent not reality (Postmortem #50)

[Copilot]

Pull request overview

This PR reduces noisy MSBuild warnings during JDK discovery by skipping paths that exist but aren’t directories (e.g., files or broken symlinks) before attempting to construct JdkInfo, and adds coverage for the regression case.

Changes:

• Add an early Directory.Exists guard in JdkInfo.TryGetJdkInfo, logging skips at Verbose instead of emitting a Warning via exception handling.
• Add a new NUnit test to ensure JI_JAVA_HOME pointing to a non-directory path does not generate a warning.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/Xamarin.Android.Tools.AndroidSdk/JdkInfo.cs	Adds a directory-existence guard to avoid warning-level logs when a candidate JDK path isn’t a directory.
tests/Xamarin.Android.Tools.AndroidSdk-Tests/JdkInfoTests.cs	Adds a regression test covering JI_JAVA_HOME set to a temp file path to ensure no warning is logged for that path.

[Copilot]

The new verbose message wraps locator in backticks, but several call sites already pass locator strings that include backticks (e.g. "/usr/libexec/java_home -X"), which results in doubled quoting like /usr/libexec/java_home -X in logs. Consider removing the extra backticks around {locator} (or ensuring locators are passed without embedded backticks) to keep verbose output readable/consistent.

Suggested change

	logger (TraceLevel.Verbose, $"Skipping JDK path `{path}` from `{locator}`: path does not exist or is not a directory.");
	logger (TraceLevel.Verbose, $"Skipping JDK path `{path}` from {locator}: path does not exist or is not a directory.");

[Copilot]

The test comment says “no Warning-level message should be logged”, but the assertion only verifies that no warning contains the temp file path (warnings from other discovery sources could still occur). Consider rewording the comment to match what’s actually asserted (e.g., “no warning should be logged for the non-directory JI_JAVA_HOME path”).

Suggested change

	// no Warning-level message should be logged.
	// no Warning-level message should be logged for that non-directory JI_JAVA_HOME path.