// ProxyUpdate is called to notify the XDS server to send a push to the specified proxy.
	// The requests may be collapsed and throttled.
	ProxyUpdate(clusterID cluster.ID, ip string)

	// RemoveShard removes all endpoints for the given shard key
	RemoveShard(shardKey ShardKey)
}

// PushRequest defines a request to push to proxies
// It is used to send updates to the config update debouncer and pass to the PushQueue.