Kapt3: Write stub class files with metadata (needed for incremental compilation)

compiler/testData/codegen/light-analysis/reflection/properties/protectedClassVar.txt

@@ -1,3 +1,4 @@
+@kotlin.Metadata
 public final class A {
     private @org.jetbrains.annotations.NotNull field v: java.lang.String
     public method <init>(@org.jetbrains.annotations.NotNull p0: java.lang.String): void
@@ -6,6 +7,7 @@ public final class A {
     protected final method setV(@org.jetbrains.annotations.NotNull p0: java.lang.String): void
 }
 
+@kotlin.Metadata
 public final class ProtectedClassVarKt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
 }