Groovy deep clone Map

class MapCloneDemo003 {
    static void main(String[] args) {
        Map map1 = [
                simpleType : 123,
                complexType : [a : 1, b : 2],
                boolType : true,
        ]

        ByteArrayOutputStream bos = new ByteArrayOutputStream()
        ObjectOutputStream oos = new ObjectOutputStream(bos)
        oos.writeObject(map1)
        oos.flush()
        oos.close()
        ByteArrayInputStream bin = new ByteArrayInputStream(bos.toByteArray())
        ObjectInputStream ois = new ObjectInputStream(bin)
        Map map2 = (Map) ois.readObject()
        ois.close()
        bos.flush()
        bos.close()
        map2.get("complexType").put('c', 13)
        map2.get("complexType").put('d', 14)

        println(map1)
        println(map2)
    }
}

[simpleType:123, complexType:[a:1, b:2], boolType:true]
[simpleType:123, complexType:[a:1, b:2, c:13, d:14], boolType:true]