Gson does not detect duplicate keys in the nested json

Gson is unable detect duplicate keys in the nested json

See below code snippet

public static void main(String[] args) throws IOException {
    Map<String, ?> map;
    //this does not detect duplicate 'key'
    map = new Gson().fromJson("{'a':'x','aa':{'key':'x','key':'y'}}", Map.class);

    //As expected , this call fails with  Exception in thread "main" com.google.gson.JsonSyntaxException: duplicate key: a
    map = new Gson().fromJson("{'a':'x','a':'y'}", Map.class);
}

Is this the expected behavior ? If so is there any alternative to fail in the first case as well?

[pratapkishorevarma]

Please add a option, which can be set to not allow duplicate keys.

[CsabaMiomni]

+1 for the option

Don’t have any hope, Google is against the devs. Again.