I've just published danube-java v0.2.0, a Java client library for Danube Messaging, an open-source, cloud-native messaging and streaming system.

The library targets Java 21+ and leans into modern Java concurrency:

• Virtual threads (Project Loom) for all I/O, no platform thread pools, no blocking executor tuning
• Flow.Publisher<StreamMessage> as the receive API, standard JDK reactive streams, no extra dependencies
• CompletableFuture<T> for all async public API

Features:

• Producers and consumers with exclusive, shared, and failover subscription types
• Partitioned topics
• Reliable dispatch (broker holds message until ack'd)
• Schema registry — JSON Schema, Avro, Protobuf
• TLS, mTLS, JWT authentication via API key

For usge details: https://danube-docs.dev-state.com/client_libraries/clients/