[Java.Interop] Retire obsolete expression-marshaling contracts - #13058

Summary

Follow up on #13030 by retiring the remaining obsolete expression-marshaling and activation contracts. This is an intentional .NET 12 source/binary API break, without compatibility stubs. Supported Android interop uses generated callbacks and trimmable typemap activation; source searches found no consumer of the removed expression pipeline or ActivatePeer.

Remove:

• JniRuntime.JniMarshalMemberBuilder, its members, the runtime MarshalMemberBuilder property, and CreationOptions.MarshalMemberBuilder / UseMarshalMemberBuilder.
• Java.Interop.Expressions.JniValueMarshalerContext, the three expression-generation hooks on JniValueMarshaler, and their expression-only helpers and primitive/string/array overrides.
• The expression-only ColorValueMarshaler and internal IJavaObjectValueMarshaler, including their referencing attributes.
• The unused JniValueManager.ActivatePeer contract and its throwing Android/sample overrides.

Retain non-expression JniValueMarshaler / argument-state conversion, primitive/string/array functionality, CreateLocalObjectReferenceArgument, peer/reference ownership, generated callbacks, and trimmable activation. Keep GetRuntimeType, JniInstanceMethods allocation helpers, and unrelated public JNI/type-signature APIs unchanged.

Update both T4 inputs and checked-in generated files. Remove stale DynamicallyAccessedMembers requirements from all eight primitive-array CreateMarshaledValue methods: their remaining conversion path constructs a known wrapper and uses type equality/assignability, not reflective activation of the requested target type. Record contract removals through PublicAPI.Unshipped entries and the existing Mono.Android ApiCompat baseline mechanism. Replace the obsolete architecture proposal with current behavior and add migration notes. No new tests are included, per request.

Validation

All SDK/runtime validation uses this branch's own Release build and repository-pinned SDK 12.0.100-alpha.1.26480.102, not sibling outputs. Framework paths/parameters below reflect the current checkout's build configuration; this change is intended for .NET 12.

Host integration command:

./dotnet-local.sh test bin/TestRelease/net10.0/Xamarin.Android.Build.Tests.dll \
  --filter 'FullyQualifiedName~Build_WithTrimmableTypeMap_Succeeds|FullyQualifiedName~Build_TrimmableTypeMap_WithCollectionExport_Succeeds|FullyQualifiedName~Build_TrimmableTypeMap_UsesMonoAndroidImplementationMetadata|FullyQualifiedName~BindingCallbackFormatSupportsDefaultConsumer' \
  --logger 'trx;LogFileName=expression-retirement-host.trx' -v minimal

Passed: 19/19, covering CoreCLR/NativeAOT typemap builds, generated callbacks, collection exports, and implementation metadata.

Device install commands, on exclusively leased emulator-5554 (arm64, API 36):

ANDROID_SERIAL=emulator-5554 ./dotnet-local.sh build -t:Install \
  tests/Mono.Android-Tests/Mono.Android-Tests/Mono.Android.NET-Tests.csproj \
  -c Release -p:PublishAot=false -p:RuntimeIdentifier=android-arm64 \
  '-p:AdbTarget=-s emulator-5554' -m:1 -v minimal

ANDROID_SERIAL=emulator-5554 ./dotnet-local.sh build -t:Install \
  tests/Mono.Android-Tests/Mono.Android-Tests/Mono.Android.NET-Tests.csproj \
  -c Release -p:PublishAot=true -p:RuntimeIdentifier=android-arm64 \
  '-p:AdbTarget=-s emulator-5554' -m:1 -v minimal

Both installs passed. Each install was followed by its matching command below, from tests/Mono.Android-Tests/Mono.Android-Tests:

ANDROID_SERIAL=emulator-5554 ../../../dotnet-local.sh test Mono.Android.NET-Tests.csproj \
  --no-build -c Release -p:PublishAot=false -p:RuntimeIdentifier=android-arm64 \
  '-p:AdbTarget=-s emulator-5554' --report-trx \
  --results-directory ../../../bin/TestRelease/TestResults/expression-retirement-coreclr

ANDROID_SERIAL=emulator-5554 ../../../dotnet-local.sh test Mono.Android.NET-Tests.csproj \
  --no-build -c Release -p:PublishAot=true -p:RuntimeIdentifier=android-arm64 \
  '-p:AdbTarget=-s emulator-5554' --report-trx \
  --results-directory ../../../bin/TestRelease/TestResults/expression-retirement-nativeaot

CoreCLR: 924 passed, 7 existing skips, zero failures. NativeAOT: 869 passed, 7 existing skips, zero failures. TRX results confirm JNI/primitive and object arrays, constructors, callbacks/exports, exceptions, peer control blocks, and reference ownership, including all 38 constructor activation tests and 58 transferred-reference tests on both runtimes. Only the test package was uninstalled afterward.

Both T4 templates regenerate the checked-in files exactly; git diff --check passes.

Review follow-up

The runtime/SDK test results above were collected for commit 1251576d3d98f093ca1879314e12f7c97771091f. Follow-up commit ce74deda0408d0b8268adc8437d07f66a5d6627c only removes the stale primitive-array trimming annotations and their unused constant.

./dotnet-local.sh build external/Java.Interop/src/Java.Interop/Java.Interop.csproj -c Release -v minimal -p:DotNetTargetFrameworkVersion=11.0 -p:EnableTrimAnalyzer=true -m:1 passed with zero warnings/errors, including API and trimming analyzers. Regeneration matches exactly. IL comparison confirmed all 1,333 emitted method bodies remain identical after normalizing RVA addresses and compiler-generated iterator numbering; all eight public conversion APIs remain and their stale parameter attributes are absent. Full SDK/device suites were not rerun for this metadata-only follow-up.

Standalone NativeAOT sample

./dotnet-local.sh build external/Java.Interop/samples/Hello-NativeAOTFromJNI/Hello-NativeAOTFromJNI.csproj -c Release -r osx-arm64 -v minimal -p:DotNetTargetFrameworkVersion=11.0 -p:RestoreConfigFile="$PWD/NuGet.Config" -m:1 passes. Running the compiled NativeAOT library from Java passes and returns Hello from .NET NativeAOT!.

Optional publish remains failed with MSB3030 in the unchanged _NativeLibRequiresLibPrefix target: it expects Hello-NativeAOTFromJNI.dylib, but the pinned SDK emits libHello-NativeAOTFromJNI.dylib. This is not claimed to be baseline-proven; no unrelated sample naming-target fix is included. The sample build and actual JNI execution validate the changed override removal.

Pull Request
title and
description
should follow the
commit-messages.md workflow documentation, and in particular should include:

• Useful description of why the change is necessary.
• Links to issues fixed
• Unit tests

No issue is closed. Existing unit/integration/runtime coverage was run; no new tests were added.