src/share/classes/com/sun/tools/javac/comp/MemberEnter.java

@@ -463,11 +463,12 @@
         JCMethodDecl valueOf = make.
             MethodDef(make.Modifiers(Flags.PUBLIC|Flags.STATIC),
                       names.valueOf,
                       make.Type(tree.sym.type),
                       List.<JCTypeParameter>nil(),
-                      List.of(make.VarDef(make.Modifiers(Flags.PARAMETER),
+                      List.of(make.VarDef(make.Modifiers(Flags.PARAMETER |
+                                                         Flags.MANDATED),
                                             names.fromString("name"),
                                             make.Type(syms.stringType), null)),
                       List.<JCExpression>nil(), // thrown
                       null, //make.Block(0, Tree.emptyList.prepend(make.Return(make.Ident(names._null)))),
                       null);