Fix up suppression for trimming warnings

Author: captainsafia

src/Http/Routing/src/ValidationEndpointFilterFactory.cs

@@ -12,7 +12,6 @@ internal static class ValidationEndpointFilterFactory
 {
     private const string ValidationContextJustification = "The DisplayName property is always statically initialized in the ValidationContext through this codepath.";
 
-    [UnconditionalSuppressMessage("Trimming", "IL2026:Members annotated with 'RequiresUnreferencedCodeAttribute' require dynamic access otherwise can break functionality when trimming application code", Justification = ValidationContextJustification)]
     public static EndpointFilterDelegate Create(EndpointFilterFactoryContext context, EndpointFilterDelegate next)
     {
         var parameters = context.MethodInfo.GetParameters();
@@ -58,7 +57,7 @@ public static EndpointFilterDelegate Create(EndpointFilterFactoryContext context
                 // initialize an explicit DisplayName. We can suppress the warning here.
                 // Eventually, this can be removed when the code is updated to
                 // use https://github.com/dotnet/runtime/issues/113134.
-                var validationContext = new ValidationContext(argument, context.HttpContext.RequestServices, items: null) { DisplayName = validatableParameter.DisplayName };
+                var validationContext = CreateValidationContext(argument, validatableParameter, context.HttpContext.RequestServices);
                 validatableContext.ValidationContext = validationContext;
                 await validatableParameter.Validate(argument, validatableContext);
             }
@@ -73,4 +72,14 @@ public static EndpointFilterDelegate Create(EndpointFilterFactoryContext context
             return next;
         };
     }
+
+    /// <remarks>
+    /// ValidationContext is not trim-friendly in codepaths that don't
+    /// initialize an explicit DisplayName. We can suppress the warning here.
+    /// Eventually, this can be removed when the code is updated to
+    /// use https://github.com/dotnet/runtime/issues/113134.
+    /// </remarks>
+    [UnconditionalSuppressMessage("Trimming", "IL2026:Members annotated with 'RequiresUnreferencedCodeAttribute' require dynamic access otherwise can break functionality when trimming application code", Justification = ValidationContextJustification)]
+    private static ValidationContext CreateValidationContext(object argument, ValidatableParameterInfo validatableParameter, IServiceProvider serviceProvider)
+        => new(argument, serviceProvider, items: null) { DisplayName = validatableParameter.DisplayName };
 }