Add ability to mark query parameter as obsolete.

Jellyfin.Server/Filters/ParameterObsoleteFilter.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Linq;
+using Jellyfin.Api.Attributes;
+using Microsoft.AspNetCore.Mvc.ApiExplorer;
+using Microsoft.OpenApi.Models;
+using Swashbuckle.AspNetCore.SwaggerGen;
+
+namespace Jellyfin.Server.Filters
+{
+    /// <summary>
+    /// Mark parameter as deprecated if it has the <see cref="ParameterObsoleteAttribute"/>.
+    /// </summary>
+    public class ParameterObsoleteFilter : IOperationFilter
+    {
+        /// <inheritdoc />
+        public void Apply(OpenApiOperation operation, OperationFilterContext context)
+        {
+            foreach (var parameterDescription in context.ApiDescription.ParameterDescriptions)
+            {
+                if (parameterDescription
+                    .CustomAttributes()
+                    .OfType<ParameterObsoleteAttribute>()
+                    .Any())
+                {
+                    foreach (var parameter in operation.Parameters)
+                    {
+                        if (parameter.Name.Equals(parameterDescription.Name, StringComparison.Ordinal))
+                        {
+                            parameter.Deprecated = true;
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+    }
+}