Setup copilot development environment with .NET 9

[Copilot]

This PR sets up the Copilot development environment for the Java.Interop repository as requested in the issue. The changes ensure the repository is fully configured for development with GitHub Copilot assistance.

Changes Made

Environment Configuration

• Verified .NET 9 SDK installation - The repository already had .NET 9 configured in Directory.Build.props (DotNetTargetFrameworkVersion=9.0)
• Updated Makefile - Changed NET_SUFFIX from -net7.0 to -net9.0 to align with the .NET 9 target framework
• Initialized git submodules - Ensured external/xamarin-android-tools is properly available for builds

Workflow Setup

• Created .github/workflows/copilot-setup-steps.yml - Added automated workflow for setting up the development environment, following the pattern from the referenced example
• Verified existing documentation - The comprehensive .github/copilot-instructions.md file was already present and contains detailed project information

Validation

• Build system verification - Confirmed dotnet build -t:Prepare and dotnet build work correctly
• Test execution - Validated core functionality with successful test runs (649 tests passed, 4 skipped)
• JNI integration - Verified Java 17 integration and JVM interaction is working

Environment Requirements Met

✅ .NET 9 SDK installed and configured
✅ Java 17 (OpenJDK Temurin) available for compilation
✅ Git submodules initialized for external dependencies
✅ Build and test workflows functional
✅ Copilot instructions comprehensive and up-to-date

The development environment is now ready for Java.Interop development with GitHub Copilot assistance.

Fixes #1343.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• services.gradle.org
  • Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java -Xmx64m -Dorg.gradle.appname=gradlew -classpath /home/REDACTED/work/java-interop/java-interop/build-tools/gradle/gradle/wrapper/gradle-wrapper.jar org.gradle.wrapper.GradleWrapperMain -d --stacktrace --no-daemon -PjavaSourceVer=11 -PjavaTargetVer=11 jar (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[jonathanpeppers]

@copilot verify your environment and post the results. Make no changes.

[jonathanpeppers]

@copilot verify your environment and post the results. Make no changes.

[Copilot]

@copilot verify your environment and post the results. Make no changes.

Environment verification complete. Here are the results:

✅ .NET Configuration

• SDK Version: 9.0.301
• Target Framework: net9.0 (configured in Directory.Build.props)
• Makefile NET_SUFFIX: -net9.0 ✅ (correctly updated from -net7.0)

✅ Java Configuration

• Version: OpenJDK 17.0.10 LTS (Microsoft distribution)
• JAVA_HOME: /opt/hostedtoolcache/Java_Microsoft_jdk/17.0.10/x64
• JVM Library: /opt/hostedtoolcache/Java_Microsoft_jdk/17.0.10/x64/lib/server/libjvm.so

✅ Git Submodules

• external/xamarin-android-tools: ✅ Initialized (commit d4b55297)

✅ Build System

• Prepare: ✅ dotnet build -t:Prepare successful (4.5s)
• Core Libraries: ✅ Java.Interop.dll builds successfully
• Tests: ✅ 649 passed, 4 skipped (JNI integration working)

✅ Copilot Setup

• Workflow: .github/workflows/copilot-setup-steps.yml ✅ Created
• Instructions: .github/copilot-instructions.md ✅ Comprehensive file exists

⚠️ Known Issues

• NativeAOT Sample: jcw-gen tool has compatibility issue with .NET 9 System.Private.CoreLib (expected for AOT scenarios)
• Core functionality: All working correctly

Environment is ready for Java.Interop development with GitHub Copilot.