Kotlin Sealed-class Deserialization helper

NB. Gradle cannot run on Java 11 (Requires Java 8)

What is it?

A general deserializer plugin for Kotlin and Jackson. Allows for more idiomatic Kotlin to be written without the need to write a specialised serializer each time. Just plug in the sealed class and off you go.

Example

Create a sealed class

sealed class Vehicles {
    data class Ferrari(val colour: String, val price: Int) : Vehicles()
    data class Golfcart(val colour: String?) : Vehicles()
    data class Motorcycle(val colour: String, val topSpeed: Int, val sideCarName: String?): Vehicles()
}

and register as a custom deserializer

val objectMapper = jacksonObjectMapper()

val vehicleSealedClassDeserializer: SimpleModule = 
    SimpleModule().addDeserializer(
        Vehicles::class.java,
        Deserializer(Vehicles::class)
    )
objectMapper.registerModule(vehicleSealedClassDeserializer)

and use as required (without building a custom deserializer each time).

val json = """{
              |"colour": "grey",
              |"price": 300000  
              |}""".trimMargin()

val myVehicle: Vehicle = objectMapper.readValue(json)

when (myVehicle) {
    is Ferrari -> println("I should buy a Tesla")
    is Golfcart -> throw Error("I don't like driving to work like this")
    is Motorcycle -> println("This is gooooood!")
}

Still to do

1. Handle default arguments that are other than nulls.
2. Select correct subclass from sealed class.
3. Handle objects recursively.
4. Handle arrays using some sort of iteration.
5. Handle object serialisation methods for special datatypes (BigTime, Time, etc.)
6. Support Floats.