在golang中构造复杂的JSON解析

I have a valid JSON, which I don't know how to parse in json.Unmarshal (golang):

{
   "method": "notice",
   "params": [0, [{
           "previous": "12345",
           "timestamp": "2017-12-12T05:49:09",
           "witness": "12345",
           "transaction_merkle_root": "ffff",
           "extensions": [],
           "witness_signature": "12345"
   }]]
}

All I can do is:

type MyJSON struct {
    Method string        `json:"method"`
    Params []interface{} `json:"params"`
}

I will be really thankful if somebody help me to write correct MyJSON type to parse all other fields through golang's json.Unmarshal. It's way too complex to me :(