{
  "topology_description": {
    "type": "ReplicaSetNoPrimary",
    "servers": [
      {
        "address": "b:27017",
        "avg_rtt_ms": 5,
        "type": "PossiblePrimary"
      }
    ]
  },
  "operation": "read",
  "read_preference": {
    "mode": "Nearest",
    "tag_sets": [
      {}
    ]
  },
  "suitable_servers": [],
  "in_latency_window": []
}