Support KClass.nestedClasses

core/builtins/src/kotlin/reflect/KClass.kt

@@ -49,6 +49,11 @@ public interface KClass<T : Any> : KDeclarationContainer, KAnnotatedElement {
      */
     public val constructors: Collection<KFunction<T>>
 
+    /**
+     * All classes declared inside this class. This includes both inner and static nested classes.
+     */
+    public val nestedClasses: Collection<KClass<*>>
+
     /**
      * The instance of the object declaration, or `null` if this class is not an object declaration.
      */