What is Object Store in Mule 4 and what are its use cases?

Object Store is a key-value storage mechanism in Mule 4 for persisting state across flow executions. Types:

1. In-Memory Object Store: Temporary storage within a single Mule runtime instance — data lost on restart. Fastest.
2. Persistent Object Store (on-premises): Persists to disk — survives restarts.
3. CloudHub Object Store v2: Fully managed, persistent, distributed store available across all CloudHub workers of the same application. Operations: store, retrieve, contains, remove, retrieve all keys, clear. TTL (time to live) can be set per entry. Use cases:
4. Idempotency — store processed message IDs to prevent duplicate processing.
5. Caching access tokens between OAuth calls.
6. Session state for multi-step flows.
7. Aggregator state. Accessible via the Object Store Connector in Anypoint Studio.