How to fetch and inspect mongodb index options using the go mongo driver

I need to get all indexes of a specific collection and inspect their index options using the go mongo driver (go.mongodb.org/mongo-driver/mongo)

Here is the code I am using:

cur, err := collection.Indexes().List(ctx)
if err != nil {
   return err
}

for cur.Next(ctx) {
	index := &mongo.IndexModel{}
	if err := cur.Decode(index); err != nil {
		return fmt.Errorf("could not decode index: %w", err)
	}

   // access index.Options
   // ...
}

However, the index variable is empty, so I guess it could not be decoded into the IndexModel type. I don't get an error either. Can somebody give advice on how to do it correctly?

I have a collection with indexes as listed in mongo shell:

[
        {
                "v" : 2,
                "key" : {
                        "_id" : 1
                },
                "name" : "_id_",
                "ns" : "test.books"
        },
        {
                "v" : 2,
                "unique" : true,
                "key" : {
                        "author" : 1,
                        "title" : 1
                },
                "name" : "author_1_title_1",
                "ns" : "test.books"
        }
]

The same indexes listed using golang:

collection := client.Database("test").Collection("books")
indexView := collection.Indexes()
opts := options.ListIndexes().SetMaxTime(2 * time.Second)
cursor, err := indexView.List(context.TODO(), opts)

if err != nil {
	log.Fatal(err)
}

var result []bson.M
if err = cursor.All(context.TODO(), &result); err != nil {
	log.Fatal(err)
}

for _, v := range result {
	for k1, v1 := range v {
		fmt.Printf("%v: %v\n", k1, v1)
	}
	fmt.Println()
}

The output is:

v: 2
key: map[_id:1]
name: _id_
ns: test.books

v: 2
unique: true
key: map[author:1 title:1]
name: author_1_title_1
ns: test.books

<hr>

[ EDIT ADD ] This is slightly different version result loop with map printed as key-values:

for _, v := range result {
	for k1, v1 := range v {
		if reflect.ValueOf(v1).Kind() == reflect.Map {
			v1a := v1.(primitive.M)
			fmt.Printf("%v: {\n", k1)
			for k2, v2 := range v1a {
				fmt.Printf("  %v: %v\n", k2, v2)
			}
			fmt.Printf("}\n")
		} else {
			fmt.Printf("%v: %v\n", k1, v1)
		}
	}
	fmt.Println()
}

The output:

key: {
  _id: 1
}
name: _id_
ns: test.books
v: 2

v: 2
unique: true
key: {
  title: 1
  author: 1
}
name: author_1_title_1
ns: test.books

The driver also exposes ListSpecifications method. It returns the IndexSpecification with index information.

collection.Indexes().ListSpecifications(ctx)