Got rid of default Hierarchy Serializer/Deserializers from DefaultTypeAdapters.
Got rid of methods for gettting default serializers/deserializers/instance creators. Instead we reuse the static final instances.
Fixed warnings in TypeAdapters where a parameterized type T was hiding the parameterized T in methods.
Removed support to unwrap single element array of enums into enum values. Also removed the test that verifies this behavior.