Delta XDS Fails to Apply Correct Configuration Upon Reconnecting to Control Plane

[kunalgaurav18]

I am working on implementing delta XDS using a java control plane. I am using the setSnapshot method in SimpleCache to send the dynamic configuration to the envoy proxy over GRPC. The api_type in the envoy configuration is set to DELTA_GRPC.

Steps to Reproduce the Issue

1. Start the xDS server.
2. Create an Envoy proxy with a bootstrap configuration to connect to the xDS server.
3. Submit a snapshot using SimpleCache.setSnapshot with the cluster name cluster-x.
4. Verify that the configuration dump details for cluster-x are present as expected.
5. Shut down the xDS server.
6. Restart the xDS server.
7. Submit another snapshot using SimpleCache.setSnapshot with the cluster name cluster-y.
8. Verify that the configuration dump details for both cluster-x and cluster-y are present.

Expectations

The cluster named cluster-x should have been removed. This behavior is observed when the xDS server state remains unchanged without restarting.