{
    "error": true,
    "read_preference": {
        "maxStalenessSeconds": 120,
        "mode": "Nearest"
    },
    "topology_description": {
        "servers": [
            {
                "address": "a:27017",
                "avg_rtt_ms": 5,
                "lastUpdateTime": 0,
                "lastWrite": {
                    "lastWriteDate": {
                        "$numberLong": "1"
                    }
                },
                "maxWireVersion": 5,
                "type": "RSPrimary"
            },
            {
                "address": "b:27017",
                "avg_rtt_ms": 5,
                "lastUpdateTime": 0,
                "lastWrite": {
                    "lastWriteDate": {
                        "$numberLong": "1"
                    }
                },
                "maxWireVersion": 4,
                "type": "RSSecondary"
            }
        ],
        "type": "ReplicaSetWithPrimary"
    }
}