perf: replace Activator.CreateInstance with direct constructor in ApiResponse.Create

Refit.Benchmarks/Refit.Benchmarks.csproj

@@ -4,7 +4,7 @@
 
     <PropertyGroup>
       <OutputType>Exe</OutputType>
-      <TargetFrameworks>net8.0</TargetFrameworks>
+      <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
       <IsPackable>false</IsPackable>
       <NoWarn>$(NoWarn);CS1591</NoWarn>
     </PropertyGroup>

Refit/ApiResponse.cs

@@ -10,20 +10,12 @@
         internal static T Create<T, TBody>(
             HttpRequestMessage request,
             HttpResponseMessage? resp,
-            object? content,
+            TBody? content,
             RefitSettings settings,
             ApiExceptionBase? error = null
         )
         {
-            return (T)
-                Activator.CreateInstance(
-                    typeof(ApiResponse<TBody>),
-                    request,
-                    resp,
-                    content,
-                    settings,
-                    error
-                )!;
+            return (T)(object)new ApiResponse<TBody>(request, resp, content, settings, error);
         }
     }
 
@@ -210,7 +202,7 @@
 #endif
             out ApiRequestException error)
         {
             error = Error as ApiRequestException;
             return error != null;
         }
 
@@ -226,7 +218,7 @@
 #endif
             out ApiException error)
         {
             error = Error as ApiException;
             return error != null;
         }
 
@@ -248,7 +240,7 @@
                         .Create(
                             request,
                             request.Method,
                             response,
                             Settings
                         )
                         .ConfigureAwait(false);

Refit/RequestBuilderImplementation.cs

@@ -407,7 +407,7 @@ object itemValue
                         return ApiResponse.Create<T, TBody>(
                             rq,
                             resp,
-                            null,
+                            default,
                             settings,
                             new ApiRequestException(rq, rq.Method, settings, ex)
                         );