The topology visualization api end point ( /api/v1/topology/TOPOLOGY-ID/visualization ) does not return correct "stats" values for "system" components __system and __acker.
See the following example correct response for a spout or bolt within a topology, shorten for brevity. Under the stats key it lists all of the instances of that component that is deployed.
See the following response for the __system and __acker components. They do not correctly list any entries under the stats key.