bson.go
func (id *ObjectId) DeepCopy() *ObjectId {
	if id == nil {
		return nil
	}
	out := new(ObjectId)
	id.DeepCopyInto(out)
	return out
}
func (id *ObjectId) DeepCopy() *ObjectId {
	if id == nil {
		return nil
	}
	out := new(ObjectId)
	id.DeepCopyInto(out)
	return out
}
// DeepCopy copies the receiver into a new ObjectId.