Nested generic type Issue

[brianyu0717]

Hi, just noticed an issue while using nested types e.g.

data class User(val id: String)

val a = gson.fromJson<List<List<User>>>("[\n" +
            "  [\n" +
            "    {\n" +
            "      \"id\": \"u-abcd\"\n" +
            "    }\n" +
            "  ]\n" +
            "]\n")

Expecting a to be of type ArrayList<ArrayList<User>>> however I'm getting ArrayList<ArrayList<LinkedTreeMap<etc... as per Gson>>> It looks like it's not getting past the 'first' level generic type.

[SalomonBrys]

This has to do with the fact that, in kotlin, List<T> is actually List<out T>, meaning it has declaration site variance.

• In Java new TypeToken<List<User>>(){}.getType() returns java.util.List<com.you.User>
• In Kotlin, object : TypeToken<List<User>>(){}.type returns java.util.List<? extends com.you.User>

This will be corrected in Kotson 2.5.0, thanks for the report ;)

[SalomonBrys]

Fixed in 2.5.0