Summary

Align the C# model, visitors, and RPC layer so that both sides (Java and C#/.NET) use identical shapes. This eliminates workarounds where the C# RPC sender/receiver had to split, merge, or fabricate fields to bridge structural differences.

Asymmetries fixed

Model consolidations (Cs.java)

1. BlockScopeNamespaceDeclaration + FileScopeNamespaceDeclaration → NamespaceDeclaration — Java had two separate types; C# had one NamespaceDeclaration. Merged into a single Cs.NamespaceDeclaration on the Java side. Removed the RegisterJavaTypeName override that mapped NamespaceDeclaration → Cs$BlockScopeNamespaceDeclaration.
2. CompilationUnit.externs, .usings, .attributeLists removed — These were redundant top-level fields; externs, usings, and attribute lists are already represented as statements within CompilationUnit.members. The C# side never had these separate fields.
3. NamespaceDeclaration.externs and .usings removed — Same redundancy as CompilationUnit: these were split out on the Java side but are just members on the C# side. The C# RPC sender/receiver had workaround code to filter UsingDirective vs non-UsingDirective members and merge them back — now removed.
4. UsingDirective.unsafe field removed — Java modeled an unsafe left-padded boolean that the C# side never had. The C# sender fabricated a JLeftPadded<bool>(Space.Empty, false) dummy, and the receiver consumed and discarded it. Both workarounds removed.
5. Cs.Try and Cs.Try.Catch removed — These were Java-only duplicates of J.Try / J.Try.Catch. The C# side uses the standard J.Try tree. Removed the redundant Cs types along with their visitor methods, RPC sender/receiver, and iso-visitor overrides.

J model alignment (J.cs on the C# side)

6. J.Package.Expression: JRightPadded<Expression> → Expression — Java side uses a plain Expression; C# had an extra right-padding wrapper. Parser, printer, visitor, and RPC updated.
7. J.EnumValue.Initializer: JLeftPadded<Expression>? → NewClass? — Java side uses a direct NewClass?; C# had an extra left-padding wrapper. Printer no longer manually prints = and spacing — delegates to the NewClass visit.
8. J.Try.Resources: JContainer<NameTree>? → JContainer<Try.Resource>? — Java side wraps try-with-resources in a Try.Resource node (holding variableDeclarations + terminatedWithSemicolon). Added the missing Try.Resource class to C# J.cs, plus VisitTryResource in both JavaSender.cs and JavaReceiver.cs.
9. J.NewClass.Clazz: TypeTree? → J? — Java side types this as J? (since the clazz can be a J.ParameterizedType which doesn't implement TypeTree on the C# side). Updated model, visitor, and RPC.

RPC alignment

10. C# CSharpSender.VisitNamespaceDeclaration — Removed workaround that split members into separate externs/usings/non-using lists for transmission. Now sends name, members, end — matching the Java receiver.
11. C# CSharpReceiver.VisitNamespaceDeclaration — Removed workaround that received separate externs/usings/members lists and merged them back into a single members list.
12. C# CSharpSender.VisitUsingDirective — Removed fabricated JLeftPadded<bool>(false) for the unsafe field.
13. C# CSharpReceiver.VisitUsingDirective — Removed consume-and-discard of the unsafe field.
14. CSharpRpcTest timeout — Increased RPC timeout from 60s to 120s to fix transient flake in parsePragmaWarningMultipleCodes.

Location enum cleanup

15. Removed CsSpace.Location / CsRightPadded.Location / CsLeftPadded.Location entries for deleted types: BLOCK_SCOPE_NAMESPACE_DECLARATION_*, FILE_SCOPE_NAMESPACE_DECLARATION_*, COMPILATION_UNIT_EXTERNS_*, COMPILATION_UNIT_USINGS_*, USING_DIRECTIVE_UNSAFE. Added NAMESPACE_DECLARATION_* replacements.

Test plan

• Existing CSharpRpcTest tests pass (including parsePragmaWarningMultipleCodes with increased timeout)
• CSharpRecipeTest passes with updated model references
• C# side compiles and RPC round-trips correctly