Reintroduce flattening for Java

Source/DafnyCore/Backends/Java/JavaCodeGenerator.cs

@@ -4322,5 +4322,19 @@ protected class ClassWriter : IClassWriter {
  catchBlock.WriteLine($"dafny.DafnySequence<Character> {haltMessageVarName} = dafny.DafnySequence.asString(e.getMessage());");
  TrStmt(recoveryBody, catchBlock);
  }
+
+ protected override void EmitNestedMatchExpr(NestedMatchExpr match, bool inLetExprBody, ConcreteSyntaxTree output,
+ ConcreteSyntaxTree wStmts) {
+ EmitExpr(match.Flattened, inLetExprBody, output, wStmts);
+ }
+
+ protected override void TrOptNestedMatchExpr(NestedMatchExpr match, Type resultType, ConcreteSyntaxTree wr, ConcreteSyntaxTree wStmts,
+ bool inLetExprBody, IVariable accumulatorVar) {
+ TrExprOpt(match.Flattened, resultType, wr, wStmts, inLetExprBody, accumulatorVar);
+ }
+
+ protected override void EmitNestedMatchStmt(NestedMatchStmt match, ConcreteSyntaxTree writer) {
+ TrStmt(match.Flattened, writer);
+ }
  }
 }