Got at least one data fetching method working; turns out, we can't use a patched LogicStack to get the data

Vendor/EmbedIO-3.5.2/WebApi/IRequestDataAttribute`2.cs

@@ -0,0 +1,25 @@
+using System.Threading.Tasks;
+
+namespace EmbedIO.WebApi
+{
+    /// <summary>
+    /// Represents an attribute, applied to a parameter of a web API controller method,
+    /// that causes the parameter to be passed deserialized data from a request.
+    /// </summary>
+    /// <typeparam name="TController">The type of the controller.</typeparam>
+    /// <typeparam name="TData">The type of the data.</typeparam>
+    /// <seealso cref="IRequestDataAttribute{TController}"/>
+    public interface IRequestDataAttribute<in TController, TData>
+        where TController : WebApiController
+        where TData : class
+    {
+        /// <summary>
+        /// Asynchronously obtains data from a controller's context.
+        /// </summary>
+        /// <param name="controller">The controller.</param>
+        /// <param name="parameterName">The name of the parameter that has to receive the data.</param>
+        /// <returns>a <see cref="Task"/> whose result will be the data
+        /// to pass as a parameter to a controller method.</returns>
+        Task<TData?> GetRequestDataAsync(TController controller, string parameterName);
+    }
+}