}
		}
	} else {
		// If there is a specific pod name in ResourceName, use the agent in the pod.
		if len(dr.ResourceNames) != 1 {
			return nil, fmt.Errorf("`ResourceNames` must have one element when `all` flag is turned on")
		}
		slice := strings.SplitN(dr.ResourceNames[0], ".", 2)
		if len(slice) != 2 {
			return nil, fmt.Errorf("invalid resource name format: %v", slice)
		}
		podName := slice[0]
		ns := slice[1]

This offered performance benefits that were too large to leave on the table, as well as opportunities to tune to our specific needs.

## Configuration protocol

Ztunnel, of course, needs to be dynamically configured in order to make decisions on how it should handle traffic.

does not impact the `Cluster` type, so we can skip generating `Cluster` in this case. Warning: Envoy currently has a bug that *requires* `Endpoints` to be pushed any time the corresponding `Cluster` is pushed, so this optimization is intentionally turned off in this specific case.

Finally, we determine which subset of the type we need to generate. XDS has two modes - "State of the World (SotW)" and "Delta". In SotW, we generally need to generate all resources of the type, even if only one...