Decode Msgpack to JSON golang

Question

How to serialize msgpack file to JSON on golang using github.com/vmihailenco/msgpack module

file, err := os.Open("current.msgpack")
if err != nil {
    fmt.Println(err)
}
defer file.Close()

decoder := msgpack.NewDecoder(file)
item := make(map[string]interface{})
decoder.Decode(&item)

fmt.Println(item) // output map[]

}