using System.Text.Json.Serialization;

var builder = WebApplication.CreateBuilder(args);

var app = builder.Build();

if (app.Environment.IsDevelopment()) {app.UseDeveloperExceptionPage();}

app.MapPost("/orders", async context => {
    var data = await context.Request.ReadFromJsonAsync<Order>();
    Console.WriteLine("Order received : " + data);
    await context.Response.WriteAsync(data.ToString());
});

await app.RunAsync();

public record Order([property: JsonPropertyName("orderId")] int orderId);