问找不到类型play.api.libs.json.JsObject的JsObject的Json序列化程序

EN

import org.joda.time.DateTime
import reactivemongo.bson.BSONObjectID
import play.modules.reactivemongo.json.BSONFormats._

case class GoogleToken
(
  id: Option[BSONObjectID],
  name: String,
  emailAddress: String,
  refreshToken: String,
  expires: DateTime
  )

object GoogleToken {

  import play.api.libs.json.Json

  // Generates Writes and Reads
  implicit val googleTokenFormat = Json.format[GoogleToken]
}

val query = Json.obj()
val cursor = collection.find(query).
  cursor[GoogleToken](ReadPreference.nearest).
  collect[List]()