null_from_json.kt

import com.google.gson.Gson
import com.google.gson.annotations.SerializedName

data class Q @JvmOverloads constructor(
        val i: Int,
        @SerializedName("list") val list: List<String> = emptyList()
)

fun main(args: Array<String>) {
    val gson = Gson()
    val q = gson.fromJson("{\"i\": 42}", Q::class.java)
    println(q)
    println(q.list.size) // NPE !!!
}