Config library #216 - this one uses Lombok though. POJOs from/to YAML/XML/Properties/INI/TOML/HJSON/JSON.
Java ODM / Unified persistence API: Store JSON in PostgreSQL, MariaDB, H2, Redis... or just use MongoDB like we meant you to. Technically backend-agnostic, spiritually MongoDB.
Simple pluralization library with support for the rules of 143 locales