Kentico custom macro method to return custom properties

Question

I have the following custom macro method which returns custom object 'EmailContact'

public class EmailContactMacroMethods : MacroMethodContainer
{

    [MacroMethod(typeof(EmailContact), "Get Contact Info", 1)]
    [MacroMethodParam(0, "Email", typeof(string), "Email")]
    public static EmailContact GetContactInfoByEmail(EvaluationContext context, params object[] parameters)
    {
        EmailContact email_contact = new EmailContact();
       
        if (!string.IsNullOrEmpty(ValidationHelper.GetString(parameters[0], "")))
        {            
            ContactInfo contact = ContactInfoProvider.GetContactInfo(parameters[0].ToString());

            if (contact != null)
            {

                email_contact.FirstName = contact.ContactFirstName;
                email_contact.LastName = contact.ContactLastName;
            }
        }

        return email_contact;
    }
}

Custom class

public class EmailContact : IDataContainer
{
    public object this[string columnName] { get => GetValue(columnName); set => throw new NotImplementedException(); }

    public string FirstName { get; set; }
    public string LastName { get; set; }

    public List<string> ColumnNames => new List<string>() { FirstName, LastName };

    public bool ContainsColumn(string columnName)
    {
        switch (columnName)
        {
            case "FirstName":
                return true;

            case "LastName":
                return true;

        }
        return false;
    }

    public object GetValue(string columnName)
    {
        switch (columnName)
        {
            case "FirstName":
                return FirstName;

            case "LastName":
                return LastName;

        }
        return null;
    }

    public bool SetValue(string columnName, object value)
    {
        throw new NotImplementedException();
    }

    public bool TryGetValue(string columnName, out object value)
    {
        if (columnName == "FirstName")
        {
            value = FirstName;
            return true;
        }
        else if (columnName == "LastName")
        {
            value = LastName;
            return true;
        }
        else
        {
            value = null;
            return false;
        }        

    }
}

I want the end user to be able to see the properties in the class as sugestions when they hit '.' in the editor.

At the moment, 'FirstName' or 'LastName' doesn't come up as sugestions in the dropdown list.

Custom NameSpace

 [Extension(typeof(EmailContactMacroFields))]
    [Extension(typeof(EmailContactMacroMethods))]    
    public class CustomContact : MacroNamespace<CustomContact>
    {
    }

Custom Namespace register

// Registers the custom module into the system
[assembly: RegisterModule(typeof(EmailContactMacroModule))]


    public class EmailContactMacroModule : Module
    {
        // Module class constructor, the system registers the module under the name "CustomMacros"
        public EmailContactMacroModule()
            : base("CustomMacros")
        {
        }

        // Contains initialization code that is executed when the application starts
        protected override void OnInit()
        {
            base.OnInit();

            // Registers "CustomNamespace" into the macro engine
            MacroContext.GlobalResolver.SetNamedSourceData("CustomContact", CustomContact.Instance);

        }

    }

Also, the custom method and the properties are not shown in the tree

Is there a way to fix this