{
  "schema": {
    "bsonType": "object",
    "required": ["_id", "value"],
    "properties": {
      "_id": {
        "bsonType": "string",
        "description": "key，格式：uni-id:[provider]:[appid]:[openid]:[access-token|user-access-token|session-key|encrypt-key-version|ticket]"
      },
      "value": {
        "bsonType": "object",
        "description": "字段_id对应的值"
      },
      "expired": {
        "bsonType": "timestamp",
        "description": "过期时间"
      }
    }
  }
}