feat(ExampleProject): add HttpRequest example

src/ExampleProject/HttpRequest.cs

@@ -0,0 +1,45 @@
+// Non-nullable member is uninitialized
+#pragma warning disable CS8618
+// ReSharper disable All
+
+// Example from https://github.com/dotnet/csharplang/discussions/7325.
+
+using System.Net.Http.Json;
+using System.Text.Json;
+using M31.FluentApi.Attributes;
+
+namespace ExampleProject;
+
+[FluentApi]
+public class HttpRequest
+{
+    [FluentMember(0)]
+    public HttpMethod Method { get; private set; }
+
+    [FluentMember(1)]
+    public string Url { get; private set; }
+
+    [FluentCollection(2, "Header")]
+    public List<(string, string)> Headers { get; private set; }
+
+    [FluentMember(3)]
+    public HttpContent Content { get; private set; }
+
+    [FluentMethod(3)]
+    public void WithJsonContent<T>(T body, Action<JsonSerializerOptions>? configureSerializer = null)
+    {
+        JsonSerializerOptions options = new JsonSerializerOptions(JsonSerializerDefaults.Web);
+        configureSerializer?.Invoke(options);
+        Content = new StringContent(JsonSerializer.Serialize(body));
+    }
+
+    [FluentMethod(4)]
+    [FluentReturn]
+    public HttpRequestMessage GetMessage()
+    {
+        HttpRequestMessage request = new HttpRequestMessage(Method, Url);
+        request.Content = Content;
+        Headers.ForEach(h => request.Headers.Add(h.Item1, h.Item2));
+        return request;
+    }
+}

src/ExampleProject/Program.cs

@@ -98,6 +98,22 @@
 
 Console.WriteLine(JsonSerializer.Serialize(employee));
 
+// HttpRequest
+//
+// Example from https://github.com/dotnet/csharplang/discussions/7325.
+//
+
+HttpRequestMessage message = CreateHttpRequest
+    .WithMethod(HttpMethod.Post)
+    .WithUrl("https://example.com")
+    .WithHeaders(("Accept", "application/json"), ("Authorization", "Bearer x"))
+    .WithJsonContent(
+        new { Name = "X", Quantity = 10 },
+        opt => opt.PropertyNameCaseInsensitive = true)
+    .GetMessage();
+
+Console.WriteLine(JsonSerializer.Serialize(message));
+
 // Node
 //