[xabt] use a response file when calling java r8.jar

[Copilot]

• Analyze the issue: R8 task command line exceeds 32,000 character limit
• Review existing code (D8.cs, R8.cs, JavaSourceUtils.cs for reference pattern)
• Research R8/D8 response file support (@argfile syntax)
• Implement response file support in D8 task
  • Create method to generate response file with jar inputs and lib references
  • Modify GetCommandLineBuilder to use response file for library arguments
  • Clean up response file after task execution
• Build verification - project builds successfully
• Add tests for response file functionality
  • Test that response file contains lib and input jars
  • Test that paths with spaces are handled correctly (no quoting needed)
• Run code review - addressed feedback
• Fix CI failure: Removed quoting from response file paths (R8/D8 treats each line as a complete argument)
• Use IsNullOrEmpty() extension method instead of is { Length: > 0 } pattern in D8.cs
• Add R8-specific arguments (--pg-conf, --main-dex-list, etc.) to response file in R8.cs
• Move ALL D8/R8 switches to response file (only JVM args remain on command line: -Xmx, -classpath, main class)

Original prompt

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This section details on the original issue you should resolve

<issue_title>Build error - The command line for R8 Tasks is too long. Command lines longer than 32000 chars are likely to fail.</issue_title>
<issue_description>### Android framework version

net10.0-android

Affected platform version

net10.0 android 36.1 VS2026 Insiders [11408.92]

Description

I was attempting to upgrade NuGets. In particular, Xamarin.AndroidX.AppCompat from 1.7.1.1 to 1.7.1.2, Xamarin.AndroidX.Navigation.UI 2.9 .6 to 2.9.6.1 and Xamarin.AndroidX.NavigationUI 2.9.6 to 2.9.6.1. NavigationUI should have dragged in Xamarin.Google.AndroidMaterial 1.13.1 instead of 1.13.0, which I was hoping would eliminate the warnings Google Play Console emits for every production build re Edge-To-Edge using deprecated APIs, etc. - issue #10304. The actual message is The command line for R8 Task is too long. Command lines longer than 32,000 characters are likely to fail. Try reducing the length of the command line by breaking down the call to R8 into multiple calls with fewer parameters per call.

msbuild.zip

Steps to Reproduce

N/A

Did you find any workaround?

No response

Relevant log output

```</issue_description>

<agent_instructions>Use a "response file" for passing all arguments to `r8.jar`, this should apply for both the `<R8/>` and `<D8/>` MSBuild tasks.

See this PR on a past attempt at implementing this: https://github.com/dotnet/android/pull/9546</agent_instructions>

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

<comments>
</comments>

• Fixes Build error - The command line for R8 Tasks is too long. Command lines longer than 32000 chars are likely to fail. #10700

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[Copilot]

@copilot I don't think these changes work:

       Using "D8" task from assembly "C:\a\_work\1\s\bin\Release\dotnet\packs\Microsoft.Android.Sdk.Windows\36.1.99-ci.copilot-fix-r8-command-line-erro...

Fixed in c387499. The issue was that I was adding quotes around paths with spaces in the response file, but R8/D8's response file parser treats each line as a complete argument - no quoting is needed. Removed the quoting logic from WriteArg() to match how JavaSourceUtils.cs handles response files.

[jonathanpeppers]

This is already surprisingly decent, but I reran some test lanes to get it completely green.

[jonathanpeppers]

@copilot you completely missed adding the same treatment to the <R8/> task that extends D8!

• https://github.com/dotnet/android/blob/main/src/Xamarin.Android.Build.Tasks/Tasks/R8.cs

This task should be using the same response file for all arguments -- otherwise, it will just hit the limit eventually, too!

[Copilot]

@copilot you completely missed adding the same treatment to the <R8/> task that extends D8!

• https://github.com/dotnet/android/blob/main/src/Xamarin.Android.Build.Tasks/Tasks/R8.cs
  ...

Fixed in 75f4235. Modified R8.cs to override CreateResponseFile() instead of GetCommandLineBuilder(), so all R8-specific arguments (--pg-conf, --main-dex-list, --main-dex-rules, --no-tree-shaking, --no-minification, etc.) are now also written to the response file.