Remove Java.Base

[simonrozsival]

Stacked on #1447 (remove-java-runtime-environment).

Summary

• Remove the standalone Java.Base binding assembly and generated reference API file.
• Remove Java.Base from the solution and documentation/tooling references.
• Remove Java.Interop.Sdk's special-case Java.Base reference forwarding.
• Clean stale Java.Base-specific comments in generator/runtime code.

Rationale

Java.Base only supported the standalone desktop/JRE binding path. With #1447 removing Java.Runtime.Environment and the standalone JVM runtime surface, the in-repo java.base binding is no longer needed by the remaining Java.Interop or dotnet/android-focused workflows.

Validation

• dotnet build -t:Prepare
• dotnet build src/Java.Interop/Java.Interop.csproj --no-restore
• dotnet build tests/Java.Interop-Tests/Java.Interop-Tests.csproj --no-restore
• dotnet build tests/generator-Tests/generator-Tests.csproj --no-restore
• dotnet test tests/Java.Interop-Tests/Java.Interop-Tests.csproj --no-build — 669 passed, 0 failed, 4 skipped

dotnet build Java.Interop.sln still hits the same local baseline failures seen on #1447: NativeTiming CMake compiler probe (ld: library 'c++' not found) and Xamarin.Android.Tools.Bytecode-Tests Gradle/Kotlin setup. No Java.Base-related build errors surfaced.

[Copilot]

Pull request overview

This PR removes the in-repo Java.Base binding assembly (and its associated generated/transform inputs) now that the standalone desktop/JRE binding path has been retired, and cleans up remaining solution/tooling/docs references to it.

Changes:

• Remove the src/Java.Base project (csproj/targets) and Java.Base-specific transform inputs/files.
• Remove Java.Base from the solution and SDK/tooling integration points.
• Clean up stale Java.Base-specific comments in generator/runtime and repo documentation.

Show a summary per file

File	Description
tools/generator/SourceWriters/GenericExplicitInterfaceImplementationProperty.cs	Updates a comment to remove Java.Base mention while preserving existing JavaInterop1 workaround explanation.
src/Java.Interop/Java.Interop/JniPeerMembers.JniInstanceMethods.cs	Removes stacktrace comment lines that referenced deleted Java.Base test/project paths.
src/Java.Base/Transforms/methodmap.csv	Deleted as part of removing Java.Base binding transforms.
src/Java.Base/Transforms/Metadata.xml	Deleted as part of removing Java.Base binding transforms.
src/Java.Base/Transforms/map.csv	Deleted as part of removing Java.Base binding transforms.
src/Java.Base/Transforms/enumflags	Deleted as part of removing Java.Base binding transforms.
src/Java.Base/Java.Lang/Throwable.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.Lang/Thread.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.Lang/StringBuilder.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.Lang/StringBuffer.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.Lang/String.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.Lang/Object.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.Lang/Long.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.Lang/Integer.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.Lang/ICharSequence.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.Lang/Float.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.Lang/Double.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.Lang/Class.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.IO/Writer.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.IO/PrintStream.cs	Deleted Java.Base-specific partial binding code.
src/Java.Base/Java.Base.targets	Deleted build logic used to generate/build Java.Base bindings.
src/Java.Base/Java.Base.csproj	Deleted Java.Base project definition.
Java.Interop.sln	Removes the Java.Base project and associated solution configuration entries.
build-tools/Java.Interop.Sdk/Sdk/Sdk.targets	Removes Java.Base-specific reference forwarding logic from the SDK target.
.github/skills/build-and-test/SKILL.md	Removes Java.Base-Tests from the list of common test projects.
.github/copilot-instructions.md	Removes Java.Base from the documented repository structure.

Copilot's findings

Comments suppressed due to low confidence (1)

build-tools/Java.Interop.Sdk/Sdk/Sdk.targets:156

• @(_Ref, ' ') is still included in the generator Exec command, but _Ref is no longer defined/populated anywhere in this target after removing the Java.Base special-case. This makes the command line harder to reason about and suggests a missing (or removed) feature for passing -r references.

    <ItemGroup>
      <!-- I can't find a good way to trim the trailing `\`, so append with `.` so we can sanely quote for $(_Libpath) -->
      <_RefAsmDir Include="@(ReferencePathWithRefAssemblies->'%(RootDir)%(Directory).'->Distinct())" />
      <_Lib Include="@(_RefAsmDir->'-L &quot;%(Identity)&quot;')" />
    </ItemGroup>
    <Exec
        Command="$(DotnetToolPath) $(Generator) $(_GenFlags) $(_ApiLevel) $(_Out) @(_Lib, ' ') @(_Ref, ' ') $(_Codegen) $(_Assembly) $(_TypeMap) $(_LangFeatures) $(_Dirs) $(_Api) $(_WithJavadocXml)"
        IgnoreStandardErrorWarningFormat="True"

• Files reviewed: 26/27 changed files
• Comments generated: 0