Summary:

• Removed updateConfig and setConfigProperty — mutation belongs on the SDK implementation, not the API, analogous to how SdkTracerProvider.shutdown() doesn't appear on TracerProvider
• updateConfig and setConfigProperty consolidated into a single setConfig(String path, Object value) — the path includes the key as its final segment, so callers no longer split path from key; accepts String, Boolean, Long, Double, Integer, DeclarativeConfigProperties, or a List thereof; validates that the type of an existing value does not change
• Replaced AtomicReference CAS loops with synchronized(lock) covering both mutation and notification dispatch, fixing out-of-order notification delivery under concurrent writers; openTelemetryConfigModel downgraded to volatile since reads remain lock-free
• shutdown() and ListenerRegistration simplified — the lock eliminates the need to iterate-and-close individual registrations on shutdown, the double-check pattern in addConfigChangeListener, and the AtomicBoolean closed guard on registrations