Use of Generics with Gson

CollectionWrapper.kt

package com.example.util

import com.example.MyList

class CollectionWrapper<T> {

    var type: Class<T>
    var list: MyList<T>

    constructor(valueType: Class<T>, list: MyList<T>) {
        type = valueType
        this.list = list
    }
}

JsonConverter.kt

package com.example.util

import com.google.gson.Gson
import com.google.gson.reflect.TypeToken
import com.example.IConverter
import com.example.ProductQuantity
import com.example.ProductSoldQuantity
import com.example.MyList

class JsonConverter : IConverter {

    override fun <T : Any?> writeValue(src: ByteArray?, valueType: Class<T>?): T =
        Gson().fromJson(src?.let { String(it) }, valueType)

    override fun writeValueAsBytes(value: Any?): ByteArray {

        return if (value !is CollectionWrapper<*>) {
            Gson().toJson(value).toByteArray()
        } else {
            when (value.type) {
                ProductSoldQuantity::class.java -> {
                    val type = object : TypeToken<WingoList<ProductSoldQuantity>>() {}.type
                    Gson().toJson(value.list, type).toByteArray()
                }

                ProductQuantity::class.java -> {
                    val type = object : TypeToken<WingoList<ProductQuantity>>() {}.type
                    Gson().toJson(value.list, type).toByteArray()
                }
                else -> ByteArray(0)
            }
        }
    }
}