[BUG] Deserialization to JSONObject when using SortedMap

xxxObject {
private SortedMap ackSampleConfig;
}

it works if the `SortedMap` is `Map`, otherwise classcastException throws.

Start by creating a minimal reproduction from the issue's object containing SortedMap and compare deserialization with Map. Trace the SortedMap handling until the ClassCastException is identified; done means the SortedMap case deserializes successfully like the Map case.

Written by the indexing model from the issue text.