Gson type adapter for post processing

gistfile1.txt

internal class RequiredFieldsTypeAdpaterFactory : TypeAdapterFactory {
    override fun <T : Any> create(gson: Gson, type: TypeToken<T>): TypeAdapter<T>? {
        val delegate = gson.getDelegateAdapter(this, type)
        val objectValidator = type.rawType.getAnnotation(EmptyObjectValidator::class.java) ?: return null

        return object: TypeAdapter<T>() {
            override fun write(out: JsonWriter?, value: T) {
                delegate.write(out, value)
            }

            override fun read(`in`: JsonReader?): T {
                val result = delegate.read(`in`)
                val postDeserializer: JsonPostDeserializer<*> = objectValidator.deserializer.javaObjectType.newInstance()
                postDeserializer.postDeserialize(result)

                return result
            }

        }
    }
}
@Retention(AnnotationRetention.RUNTIME)
@Target(AnnotationTarget.CLASS)
annotation class EmptyObjectValidator(val deserializer: KClass<out JsonPostDeserializer<*>>)

@EmptyObjectValidator(FluffValidator::class)
data class Fluff(val blah: String = "")

class FluffValidator: JsonPostDeserializer<Fluff> {
    override fun postDeserialize(type: Fluff) {
        TODO("Not yet implemented")
    }
}

interface JsonPostDeserializer<T> {
    fun postDeserialize(type: T)
}