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

compiler/testData/codegen/light-analysis/classes/classObjectInTrait.txt

@@ -1,8 +1,10 @@
+@kotlin.Metadata
 public interface C {
     public final static field Companion: C.Companion
     inner class C/Companion
 }
 
+@kotlin.Metadata
 public final static class C/Companion {
     private final static @org.jetbrains.annotations.NotNull field FOO: java.lang.String
     inner class C/Companion
@@ -10,6 +12,7 @@ public final static class C/Companion {
     public final @org.jetbrains.annotations.NotNull method getFOO(): java.lang.String
 }
 
+@kotlin.Metadata
 public final class ClassObjectInTraitKt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
 }