var attachment = new Attachment(new Uri("ldap://example.com:3333/o=eExample Industries,c=3DUS??(cn=3DBJohn Smith)"));
var calendar = new Calendar();
var vEvent = new CalendarEvent
{
    Start = new CalDateTime(DateTime.Parse("2016-07-23T07:00:00-04:00")),
    End = new CalDateTime(DateTime.Parse("2016-07-23T08:00:00-04:00")),
};
vEvent.Attachments = new List<Attachment> { attachment };
calendar.Events.Add(vEvent);

var uri = calendar
    .Events
    .First()
    .Attachments
    .Select(a => a.Uri)
    .Single();

public class SomeObject
{
    public List<string> TheList { get; }
    public int TheNumber { get; }
    public ISet<string> TheSet { get; }
    public SomeObject(List<string> theList, int theNumber, IEnumerable<string> theSet)
    {
        TheList = theList;
        TheNumber = theNumber;
        TheSet = new HashSet<string>(theSet);
    }
}

var collection = new List<string>
{
    "Foo", "Bar", "Baz", "Foo", "Bar", "Baz", "Foo", "Bar", "Baz",
    "Foo", "Bar", "Baz", "Foo", "Bar", "Baz", "Foo", "Bar", "Baz",
};
var someObject = new SomeObject(thisList: collection, theNumber: 42, theSet: collection);
var json = JsonConvert.SerializeObject(someObject);  //JSON.net

var asBytes = Encoding.UTF8.GetBytes(json);
var binaryAttachment = new Attachment(asBytes);
var calendar = new Calendar();
var vEvent = new CalendarEvent
{
    Start = new CalDateTime(DateTime.Parse("2016-07-23T07:00:00-04:00")),
    End = new CalDateTime(DateTime.Parse("2016-07-23T08:00:00-04:00")),
};
vEvent.Attachments = new List<Attachment> { attachment };
calendar.Events.Add(vEvent);

var newSomeObj = calendar
    .Events
    .First()
    .Attachments
    .Select(a => Encoding.UTF8.GetString(a.Data))
    .Select(json => JsonConvert.DeserializeObject<SomeObject>(json))
    .Single();