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

compiler/testData/codegen/light-analysis/functions/defaultargs4.txt

@@ -1,9 +1,11 @@
+@kotlin.Metadata
 public interface A {
     inner class A/DefaultImpls
     public abstract method bar(p0: int): int
     public abstract method bar2(p0: int): int
 }
 
+@kotlin.Metadata
 public final class A/DefaultImpls {
     inner class A/DefaultImpls
     public synthetic static method bar$default(p0: A, p1: int, p2: int, p3: java.lang.Object): int
@@ -11,16 +13,19 @@ public final class A/DefaultImpls {
     public synthetic static method bar2$default(p0: A, p1: int, p2: int, p3: java.lang.Object): int
 }
 
+@kotlin.Metadata
 public abstract class B {
     public method <init>(): void
     public method bar(p0: int): int
     public method bar2(p0: int): int
 }
 
+@kotlin.Metadata
 public final class C {
     public method <init>(): void
 }
 
+@kotlin.Metadata
 public final class Defaultargs4Kt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
 }