testapps/TestHttpFunction/Function.cs

using Amazon.Lambda.Core;
using Amazon.Lambda.APIGatewayEvents;
using System.Net;

// Assembly attribute to enable the Lambda function's JSON input to be converted into a .NET class.
[assembly: LambdaSerializer(typeof(Amazon.Lambda.Serialization.SystemTextJson.DefaultLambdaJsonSerializer))]

namespace TestHttpFunction;

public class Function
{

    public APIGatewayHttpApiV2ProxyResponse FunctionHandler(APIGatewayProxyRequest request, ILambdaContext context)
    {
        var response = new APIGatewayHttpApiV2ProxyResponse
        {
            StatusCode = (int)HttpStatusCode.OK,
            Body = "Making HTTP Calls",
            Headers = new Dictionary<string, string> { { "Content-Type", "text/plain" } }
        };

        return response;
    }
}