private Object writeReplace() throws ObjectStreamException {
    return new LinkedHashMap<>(this);
  }
If somebody is unlucky enough to have to serialize one of these, serialize
it as a LinkedHashMap so that they won't need Gson on the other side to
deserialize it. Using serialization defeats our DoS defence, so most apps
shouldn't use it.
lottie/src/main/java/com/airbnb/lottie/parser/moshi/LinkedHashTreeMap.java