[build] Remove Step_PrepareProps; fold values into eng/Versions.props

[jonathanpeppers]

Continues the slow xaprepare removal. Recent precedent: #11568 (CopyExtraResultFilesForCI → YAML), #11580 (configuration.mk removal), #11529 (android-platform-support consolidation, which also dropped Step_PrepareExternalGitDependencies).

What

Step_PrepareProps generated external/Java.Interop/Configuration.Override.props (inside the submodule) by substituting two placeholders into build-tools/scripts/Configuration.Java.Interop.Override.in.props. The substituted properties (_XamarinAndroidCecilVersion, UtilityOutputFullPathCoreApps, XamarinAndroidToolsDirectory) are now supplied directly via the checked-in static file external/Java.Interop.override.props, which Java.Interop's own Directory.Build.props already auto-imports via the parent-dir convention added in dotnet/java-interop#872.

The shared version values (MonoCecilVersion, AndroidPackVersion, AndroidPackVersionSuffix) move into eng/Versions.props. Directory.Build.props and external/Java.Interop.override.props both <Import> it. No duplicate-import sentinel is needed because every code path that imports Configuration.props has already loaded Directory.Build.props (either via MSBuild auto-load or via the explicit <Import> in external/xamarin-android-tools.override.props).

MicrosoftAndroidSdkPackName stays in Configuration.props (it is OS-conditioned, not version-shaped, so it doesn't belong in Versions.props). The same 3-line OS-conditioned block is mirrored privately in external/Java.Interop.override.props as _MicrosoftAndroidSdkPackName, used only to compute UtilityOutputFullPathCoreApps for the Java.Interop build.

Also dropped:

• Configurables.Paths.InstallMSBuildDir and its backing field — the only consumer was Step_PrepareProps.
• The dead UtilityOutputFullPath line in the old template — Java.Interop's TargetFrameworkDependentValues.props unconditionally routes it to $(UtilityOutputFullPathCoreApps) anyway, so it was a no-op.

Updated build-tools/scripts/XAVersionInfo.targets (the GitBlame for <AndroidPackVersion> now points at eng/Versions.props) and Documentation/guides/HowToBranch.md to reflect the moves.

Why not just <Import> Directory.Build.props from the Java.Interop override?

That was the original idea. I prototyped it: importing dotnet/android's full props chain from external/Java.Interop.override.props flips DotNetTargetFrameworkVersion from 10.0 to 11.0 inside Java.Interop, and dotnet restore Java.Interop.csproj then fails with:

NETSDK1045: The current .NET SDK does not support targeting .NET 11.0

xamarin-android-tools.override.props gets away with the same trick only because its sole csproj sets AndroidToolsDisableMultiTargeting=true, which makes the TFM-clobber harmless. Java.Interop has no equivalent escape hatch.

eng/Versions.props is collision-free with Java.Interop (verified against the submodule sources — none of the existing entries collide), has no <Import> of its own, and is the safe minimal shared file.

Verification

On Windows:

• dotnet build build-tools/xaprepare/xaprepare/xaprepare.csproj — 0 warnings, 0 errors.
• From src/Xamarin.Android.Build.Tasks/: dotnet msbuild --getProperty:MonoCecilVersion,AndroidPackVersion,AndroidPackVersionSuffix,MicrosoftAndroidSdkPackName,MicrosoftAndroidSdkOutDir — values unchanged from baseline.
• From external/Java.Interop/src/Java.Interop/:
  • dotnet msbuild --getProperty:DotNetTargetFramework,_XamarinAndroidCecilVersion,UtilityOutputFullPathCoreApps returns net10.0, 0.11.5, the expected packs/tools path.
  • dotnet restore Java.Interop.csproj succeeds (no NETSDK1045).

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com

[Copilot]

Pull request overview

Removes the xaprepare-driven Step_PrepareProps generation step by moving shared version properties into eng/Versions.props and wiring Java.Interop overrides to consume those values via a checked-in external/Java.Interop.override.props.

Changes:

• Introduced eng/Versions.props as the shared location for MonoCecilVersion, AndroidPackVersion, and MicrosoftAndroidSdkPackName, plus an _XAVersionsPropsImported sentinel to avoid duplicate-import warnings.
• Updated Directory.Build.props, Configuration.props, and external/Java.Interop.override.props to import eng/Versions.props (guarded by the sentinel).
• Deleted the obsolete Step_PrepareProps and its template input file, and updated supporting docs/targets to reference the new source of AndroidPackVersion.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
external/Java.Interop.override.props	Imports eng/Versions.props and provides static Java.Interop override properties (incl. Cecil version + tools path).
eng/Versions.props	Adds sentinel + centralizes shared version properties for dotnet/android and Java.Interop.
Documentation/guides/HowToBranch.md	Updates branching guidance to point AndroidPackVersion edits to eng/Versions.props.
Directory.Build.props	Imports eng/Versions.props and removes local definitions now centralized there.
Configuration.props	Imports eng/Versions.props with sentinel guard; removes duplicated MicrosoftAndroidSdkPackName definitions.
build-tools/xaprepare/xaprepare/Steps/Step_PrepareProps.cs	Deletes the xaprepare step that generated Java.Interop override props.
build-tools/xaprepare/xaprepare/Scenarios/Scenario_Standard.cs	Removes the deleted step from the standard scenario.
build-tools/xaprepare/xaprepare/ConfigAndData/Configurables.cs	Removes InstallMSBuildDir path that was only used by the deleted step.
build-tools/scripts/XAVersionInfo.targets	Updates GitBlame to track AndroidPackVersion in eng/Versions.props.
build-tools/scripts/Configuration.Java.Interop.Override.in.props	Deletes the unused template file previously consumed by Step_PrepareProps.

[jonathanpeppers]

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