Calling a rest method from powershell with a json object that has an array property of objects

I'm trying to mimick a c# class definition taken in on the body of a webapi call in powershell so I can call a rest method with that object represented as json. An example of the structure of json I'm trying to achieve would be:

'{
    "Name" : "Test" ,
    "Items" : [{"Key" : "Test", "Value" : "t2"},{"Key" : "Test2", "Value" : "t3"}]
}'

This json works when set to the body of the rest call in postman, if I call the powershell invokerest-method with it all fields are simply null on the webapi end.

Here is my current attempt at this in powershell, note, Items is effectively a list of key value pair objects. Using the below code I just get 1 item in items, with a null name and value.

$spec = @{
    Name = 'Test' 
    Items = ,{Name = 'Test', Value = 't2'}, {Name = 'Test2', Value = 't3'}
}

invoke-restmethod $someurl  -Method:POST -body $spec | Write-Host

I'm fairly sure I'm missing something important with the array declaration for items on the powershell object.

Here is the rest method:

   [HttpPost]
    [Route("addorupdateitem")]
    public void Add([FromBody] ItemConfigurationDto itemconfig)
    {
        var serializeObject = Newtonsoft.Json.JsonConvert.SerializeObject(context);
        Debug.WriteLine(serializeObject);
    }

and the objects

public class ItemConfigurationDto
{
    public string Name { get; set; }
    public List<Item> Items { get; set; } = new List<Item>();
}

public class Item
{
    public string Name { get; set; }
    public string Value { get; set; }
}