Cannot find a Java installation on your machine matching this tasks requirements: {languageVersion=17...

I'm not entirely sure what happened, but I recently updated to the latest Skip version and started getting the following error when trying to compile my project in Xcode.

* What went wrong:
Could not determine the dependencies of task ':app:packageDebug'.
> Could not create task ':app:compileDebugJavaWithJavac'.
   > Failed to calculate the value of task ':app:compileDebugJavaWithJavac' property 'javaCompiler'.
      > Cannot find a Java installation on your machine matching this tasks requirements: {languageVersion=17, vendor=any, implementation=vendor-specific} for MAC_OS on aarch64.
         > No locally installed toolchains match and toolchain download repositories have not been configured.

It's not clear to me why it's referencing languageVersion=17. I have the following installed:

jeff@M3-MBP Android % java --version
openjdk 21.0.3 2024-04-16
OpenJDK Runtime Environment Homebrew (build 21.0.3)
OpenJDK 64-Bit Server VM Homebrew (build 21.0.3, mixed mode, sharing)

jeff@M3-MBP Android % echo $JAVA_HOME
/opt/homebrew/Cellar/openjdk@21/21.0.3

Skip checkup seems to work properly:

[✓] Skip version 0.8.55 (= 0.8.55)
[✓] macOS version 14.5 (> 13.5.0)
[✓] Swift version 5.10 (> 5.9.0)
[✓] Xcode version 15.4 (> 15.0.0)
[✓] Xcode tools SDKs: 9
[✓] Homebrew version 4.3.7 (> 4.1.0)
[✓] Gradle version 8.8 (> 8.6.0)
[✓] Java version 21.0.3 (> 21.0.0)
[✓] Android Debug Bridge version 1.0.41 (> 1.0.40)
[✓] Android Studio version: 2023.3
[✓] Android tools SDKs: 4
[✓] Resolve dependencies (6.53s)
[✓] Build hello-skip (7.16s)
[✓] Test Swift (4.58s)
[✓] Test Kotlin (27.85s)
[✓] Archive iOS ipa (12.12s)
[✓] Assemble HelloSkip-release.ipa 37 KB
[✓] Verify HelloSkip-release.ipa 37 KB
[✓] Assembling Android apk (63.56s)
[✓] Verify HelloSkip-release.apk 12.8 MB
[✓] Check Swift Package (0.15s)
[✓] Skip 0.8.55 checkup succeeded in 122.45s

I tried initializing a new Skip app project and compiled it fine with Xcode. I'm not sure what happened to my project, but it seems odd that it would fail to use the proper Java version.

Start with the Gradle task :app:compileDebugJavaWithJavac and compare the failing project with a newly initialized Skip app, which reportedly compiles in Xcode. Check how the project selects Java 17 when Java 21 is installed. Done means the existing project compiles successfully in Xcode without the missing-toolchain error.