.NET Fiddle

CSharp · Console

/Program.cs

using Amazon.Lambda.DynamoDBEvents;
using System;
using System.Collections.Generic;
					
public class Program
{
	public static void Main()
	{
		var image = CreateBasicImage();
		var json = image.ToJson();
		Console.WriteLine(json);
	}
	
	private static Dictionary<string, DynamoDBEvent.AttributeValue> CreateBasicImage() =>
        new()
        {
            { "PublishThing", new DynamoDBEvent.AttributeValue { N = null } }, // Or new DynamoDBEvent.AttributeValue()
			{ "SomeDefaultThing", new DynamoDBEvent.AttributeValue { S = "foo" } }
        };
}