🌏 Adventure 4.9.1

Fixes 🐛

• #439 - api: Be more strict about validating nullness of appended components
• #440 - api: Don't have redundant overrides of Pointered methods
• eb867ff - text-serializer-gson: Remove use of recently added Gson method
• ce69e32 - api: Correct nullabiilty on Pointered.getOrDefault