openiddict · kevinchalet · Feb 10, 2026 · Feb 10, 2026
diff --git a/Directory.Packages.props b/Directory.Packages.props
diff --git a/sandbox/OpenIddict.Sandbox.AspNet.Client/OpenIddict.Sandbox.AspNet.Client.csproj b/sandbox/OpenIddict.Sandbox.AspNet.Client/OpenIddict.Sandbox.AspNet.Client.csproj
@@ -7,7 +7,6 @@
     <MvcBuildViews>false</MvcBuildViews>
     <ImplicitUsings>disable</ImplicitUsings>
     <NoWarn>CA3147</NoWarn>
-    <IncludePolyfills>false</IncludePolyfills>
   </PropertyGroup>
 
   <ItemGroup>

diff --git a/sandbox/OpenIddict.Sandbox.AspNet.Server/OpenIddict.Sandbox.AspNet.Server.csproj b/sandbox/OpenIddict.Sandbox.AspNet.Server/OpenIddict.Sandbox.AspNet.Server.csproj
@@ -7,7 +7,6 @@
     <MvcBuildViews>false</MvcBuildViews>
     <ImplicitUsings>disable</ImplicitUsings>
     <NoWarn>CA3147</NoWarn>
-    <IncludePolyfills>false</IncludePolyfills>
   </PropertyGroup>
 
   <ItemGroup>

diff --git a/sandbox/OpenIddict.Sandbox.AspNet.Server/Views/Authorization/Authorize.cshtml b/sandbox/OpenIddict.Sandbox.AspNet.Server/Views/Authorization/Authorize.cshtml
@@ -14,10 +14,10 @@
         foreach (var parameter in string.Equals(Request.HttpMethod, "POST", StringComparison.OrdinalIgnoreCase) ?
             from name in Request.Form.AllKeys
             from value in Request.Form.GetValues(name)
-            select new KeyValuePair<string, string>(name, value) :
+            select KeyValuePair.Create(name, value) :
             from name in Request.QueryString.AllKeys
             from value in Request.QueryString.GetValues(name)
-            select new KeyValuePair<string, string>(name, value))
+            select KeyValuePair.Create(name, value))
         {
             <input type="hidden" name="@parameter.Key" value="@parameter.Value" />
         }

diff --git a/sandbox/OpenIddict.Sandbox.AspNet.Server/Views/Authorization/EndSession.cshtml b/sandbox/OpenIddict.Sandbox.AspNet.Server/Views/Authorization/EndSession.cshtml
@@ -12,10 +12,10 @@
         foreach (var parameter in string.Equals(Request.HttpMethod, "POST", StringComparison.OrdinalIgnoreCase) ?
             from name in Request.Form.AllKeys
             from value in Request.Form.GetValues(name)
-            select new KeyValuePair<string, string>(name, value) :
+            select KeyValuePair.Create(name, value) :
             from name in Request.QueryString.AllKeys
             from value in Request.QueryString.GetValues(name)
-            select new KeyValuePair<string, string>(name, value))
+            select KeyValuePair.Create(name, value))
         {
             <input type="hidden" name="@parameter.Key" value="@parameter.Value" />
         }

diff --git a/shared/OpenIddict.Extensions/OpenIddictHelpers.cs b/shared/OpenIddict.Extensions/OpenIddictHelpers.cs
@@ -1193,7 +1193,7 @@ public FormReader(Stream stream, Encoding encoding)
             ReadNextPairImpl();
             if (ReadSucceeded())
             {
-                return new KeyValuePair<string, string>(_currentKey, _currentValue);
+                return KeyValuePair.Create(_currentKey, _currentValue);
             }
             return null;
         }
@@ -1220,7 +1220,7 @@ private void ReadNextPairImpl()
             await ReadNextPairAsyncImpl(cancellationToken);
             if (ReadSucceeded())
             {
-                return new KeyValuePair<string, string>(_currentKey, _currentValue);
+                return KeyValuePair.Create(_currentKey, _currentValue);
             }
             return null;
         }

diff --git a/shared/OpenIddict.Extensions/OpenIddictPolyfills.cs b/shared/OpenIddict.Extensions/OpenIddictPolyfills.cs
@@ -258,16 +258,6 @@ public static bool IsWindowsVersionAtLeast(int major, int minor = 0, int build =
 #endif
     }
 
-    extension(ValueTask)
-    {
-#if !SUPPORTS_VALUETASK_COMPLETED_TASK
-        /// <summary>
-        /// Gets a task that has already completed successfully.
-        /// </summary>
-        public static ValueTask CompletedTask => default;
-#endif
-    }
-
     extension<TResult>(ValueTask<TResult>)
     {
 #if !SUPPORTS_VALUETASK_COMPLETED_TASK

diff --git a/src/OpenIddict.Abstractions/Primitives/OpenIddictMessage.cs b/src/OpenIddict.Abstractions/Primitives/OpenIddictMessage.cs
@@ -152,6 +152,37 @@ public OpenIddictMessage(IEnumerable<KeyValuePair<string, string?>> parameters)
     /// </summary>
     /// <param name="parameters">The message parameters.</param>
     /// <remarks>Parameters with a null or empty key are always ignored.</remarks>
+    public OpenIddictMessage(IEnumerable<KeyValuePair<string, ImmutableArray<string?>>> parameters)
+    {
+        ArgumentNullException.ThrowIfNull(parameters);
+
+        foreach (var parameter in parameters)
+        {
+            // Ignore parameters whose name is null or empty.
+            if (string.IsNullOrEmpty(parameter.Key))
+            {
+                continue;
+            }
+
+            // Note: the core OAuth 2.0 specification requires that request parameters
+            // not be present more than once but derived specifications like the
+            // token exchange specification deliberately allow specifying multiple
+            // parameters with the same name to represent a multi-valued parameter.
+            AddParameter(parameter.Key, parameter.Value switch
+            {
+                { IsDefaultOrEmpty: true } => default,
+                      [string value]       => new OpenIddictParameter(value),
+                       [..] values         => new OpenIddictParameter(values)
+            });
+        }
+    }
+
+    /// <summary>
+    /// Initializes a new OpenIddict message.
+    /// </summary>
+    /// <param name="parameters">The message parameters.</param>
+    /// <remarks>Parameters with a null or empty key are always ignored.</remarks>
+    [Obsolete("This constructor is obsolete and will be removed in a future version.")]
     public OpenIddictMessage(IEnumerable<KeyValuePair<string, ImmutableArray<string?>?>> parameters)
     {
         ArgumentNullException.ThrowIfNull(parameters);
@@ -170,9 +201,9 @@ public OpenIddictMessage(IEnumerable<KeyValuePair<string, ImmutableArray<string?
             // parameters with the same name to represent a multi-valued parameter.
             AddParameter(parameter.Key, parameter.Value switch
             {
-                  null or []   => default,
-                [string value] => new OpenIddictParameter(value),
-                 [..] values   => new OpenIddictParameter(values)
+                  null or { IsDefaultOrEmpty: true } => default,
+                          [string value]             => new OpenIddictParameter(value),
+                           [..] values               => new OpenIddictParameter(values)
             });
         }
     }

diff --git a/src/OpenIddict.Abstractions/Primitives/OpenIddictRequest.cs b/src/OpenIddict.Abstractions/Primitives/OpenIddictRequest.cs
@@ -80,6 +80,17 @@ public OpenIddictRequest(IEnumerable<KeyValuePair<string, string?>> parameters)
     /// </summary>
     /// <param name="parameters">The request parameters.</param>
     /// <remarks>Parameters with a null or empty key are always ignored.</remarks>
+    public OpenIddictRequest(IEnumerable<KeyValuePair<string, ImmutableArray<string?>>> parameters)
+        : base(parameters)
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new OpenIddict request.
+    /// </summary>
+    /// <param name="parameters">The request parameters.</param>
+    /// <remarks>Parameters with a null or empty key are always ignored.</remarks>
+    [Obsolete("This constructor is obsolete and will be removed in a future version.")]
     public OpenIddictRequest(IEnumerable<KeyValuePair<string, ImmutableArray<string?>?>> parameters)
         : base(parameters)
     {

diff --git a/src/OpenIddict.Abstractions/Primitives/OpenIddictResponse.cs b/src/OpenIddict.Abstractions/Primitives/OpenIddictResponse.cs
@@ -79,6 +79,17 @@ public OpenIddictResponse(IEnumerable<KeyValuePair<string, string?>> parameters)
     /// </summary>
     /// <param name="parameters">The response parameters.</param>
     /// <remarks>Parameters with a null or empty key are always ignored.</remarks>
+    public OpenIddictResponse(IEnumerable<KeyValuePair<string, ImmutableArray<string?>>> parameters)
+        : base(parameters)
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new OpenIddict response.
+    /// </summary>
+    /// <param name="parameters">The response parameters.</param>
+    /// <remarks>Parameters with a null or empty key are always ignored.</remarks>
+    [Obsolete("This constructor is obsolete and will be removed in a future version.")]
     public OpenIddictResponse(IEnumerable<KeyValuePair<string, ImmutableArray<string?>?>> parameters)
         : base(parameters)
     {

diff --git a/src/OpenIddict.Client.Owin/OpenIddictClientOwinHandlers.cs b/src/OpenIddict.Client.Owin/OpenIddictClientOwinHandlers.cs
@@ -245,7 +245,7 @@ public async ValueTask HandleAsync(TContext context)
                 context.Transaction.Request = new OpenIddictRequest(
                     from parameter in request.Query
                     let values = new StringValues(parameter.Value)
-                    select new KeyValuePair<string, StringValues>(parameter.Key, values));
+                    select KeyValuePair.Create(parameter.Key, values));
             }
 
             else if (string.Equals(request.Method, "POST", StringComparison.OrdinalIgnoreCase))
@@ -279,7 +279,7 @@ from parameter in request.Query
                 context.Transaction.Request = new OpenIddictRequest(
                     from parameter in await request.ReadFormAsync()
                     let values = new StringValues(parameter.Value)
-                    select new KeyValuePair<string, StringValues>(parameter.Key, values));
+                    select KeyValuePair.Create(parameter.Key, values));
             }
 
             else

diff --git a/src/OpenIddict.Client.SystemNetHttp/OpenIddictClientSystemNetHttpHandlers.cs b/src/OpenIddict.Client.SystemNetHttp/OpenIddictClientSystemNetHttpHandlers.cs
@@ -1148,7 +1148,7 @@ from parameter in context.Transaction.Request.GetParameters()
                     let values = (ImmutableArray<string?>?) parameter.Value
                     where values is not null
                     from value in values.GetValueOrDefault()
-                    select new KeyValuePair<string?, string?>(parameter.Key, value));
+                    select KeyValuePair.Create(parameter.Key, value));
             }
 
             return ValueTask.CompletedTask;
@@ -1590,7 +1590,7 @@ public ValueTask HandleAsync(TContext context)
                         value = parameter[start..index].Trim();
                     }
 
-                    yield return new KeyValuePair<string, string?>(key, value);
+                    yield return KeyValuePair.Create<string, string?>(key, value);
                 }
             }
         }

diff --git a/src/OpenIddict.Server.Owin/OpenIddictServerOwinHandlers.cs b/src/OpenIddict.Server.Owin/OpenIddictServerOwinHandlers.cs
@@ -493,7 +493,7 @@ public ValueTask HandleAsync(TContext context)
                 context.Transaction.Request = new OpenIddictRequest(
                     from parameter in request.Query
                     let values = new StringValues(parameter.Value)
-                    select new KeyValuePair<string, StringValues>(parameter.Key, values));
+                    select KeyValuePair.Create(parameter.Key, values));
             }
 
             else
@@ -544,7 +544,7 @@ public async ValueTask HandleAsync(TContext context)
                 context.Transaction.Request = new OpenIddictRequest(
                     from parameter in request.Query
                     let values = new StringValues(parameter.Value)
-                    select new KeyValuePair<string, StringValues>(parameter.Key, values));
+                    select KeyValuePair.Create(parameter.Key, values));
             }
 
             else if (string.Equals(request.Method, "POST", StringComparison.OrdinalIgnoreCase))
@@ -578,7 +578,7 @@ from parameter in request.Query
                 context.Transaction.Request = new OpenIddictRequest(
                     from parameter in await request.ReadFormAsync()
                     let values = new StringValues(parameter.Value)
-                    select new KeyValuePair<string, StringValues>(parameter.Key, values));
+                    select KeyValuePair.Create(parameter.Key, values));
             }
 
             else
@@ -653,7 +653,7 @@ public async ValueTask HandleAsync(TContext context)
                 context.Transaction.Request = new OpenIddictRequest(
                     from parameter in await request.ReadFormAsync()
                     let values = new StringValues(parameter.Value)
-                    select new KeyValuePair<string, StringValues>(parameter.Key, values));
+                    select KeyValuePair.Create(parameter.Key, values));
             }
 
             else

diff --git a/src/OpenIddict.Validation.SystemNetHttp/OpenIddictValidationSystemNetHttpHandlers.cs b/src/OpenIddict.Validation.SystemNetHttp/OpenIddictValidationSystemNetHttpHandlers.cs
@@ -548,7 +548,7 @@ from parameter in context.Transaction.Request.GetParameters()
                     let values = (ImmutableArray<string?>?) parameter.Value
                     where values is not null
                     from value in values.GetValueOrDefault()
-                    select new KeyValuePair<string?, string?>(parameter.Key, value));
+                    select KeyValuePair.Create(parameter.Key, value));
             }
 
             return ValueTask.CompletedTask;
@@ -990,7 +990,7 @@ public ValueTask HandleAsync(TContext context)
                         value = parameter[start..index].Trim();
                     }
 
-                    yield return new KeyValuePair<string, string?>(key, value);
+                    yield return KeyValuePair.Create<string, string?>(key, value);
                 }
             }
         }

diff --git a/test/OpenIddict.Abstractions.Tests/Primitives/OpenIddictMessageTests.cs b/test/OpenIddict.Abstractions.Tests/Primitives/OpenIddictMessageTests.cs
@@ -36,8 +36,8 @@ public void Constructor_ThrowsAnExceptionForDuplicateParameters()
         {
             return new OpenIddictMessage(
             [
-                new KeyValuePair<string, OpenIddictParameter>("parameter", "Fabrikam"),
-                new KeyValuePair<string, OpenIddictParameter>("parameter", "Contoso")
+                KeyValuePair.Create("parameter", new OpenIddictParameter("Fabrikam")),
+                KeyValuePair.Create("parameter", new OpenIddictParameter("Contoso"))
             ]);
         });
 
@@ -51,7 +51,7 @@ public void Constructor_ImportsParameters()
         // Arrange and act
         var message = new OpenIddictMessage(
         [
-            new KeyValuePair<string, OpenIddictParameter>("parameter", 42)
+            KeyValuePair.Create("parameter", new OpenIddictParameter(42))
         ]);
 
         // Assert
@@ -66,7 +66,7 @@ public void Constructor_IgnoresNullOrEmptyParameterNames(string? name)
         // Arrange and act
         var message = new OpenIddictMessage(
         [
-            new KeyValuePair<string, OpenIddictParameter>(name!, "Fabrikam")
+            KeyValuePair.Create(name!, new OpenIddictParameter("Fabrikam"))
         ]);
 
         // Assert
@@ -79,8 +79,8 @@ public void Constructor_PreservesEmptyParameters()
         // Arrange and act
         var message = new OpenIddictMessage(
         [
-            new KeyValuePair<string, OpenIddictParameter>("null-parameter", (string?) null),
-            new KeyValuePair<string, OpenIddictParameter>("empty-parameter", string.Empty)
+            KeyValuePair.Create("null-parameter", new OpenIddictParameter((string?) null)),
+            KeyValuePair.Create("empty-parameter", new OpenIddictParameter(string.Empty))
         ]);
 
         // Assert
@@ -93,8 +93,8 @@ public void Constructor_CombinesDuplicateParameters()
         // Arrange and act
         var message = new OpenIddictMessage(
         [
-            new KeyValuePair<string, string?>("parameter", "Fabrikam"),
-            new KeyValuePair<string, string?>("parameter", "Contoso")
+            KeyValuePair.Create<string, string?>("parameter", "Fabrikam"),
+            KeyValuePair.Create<string, string?>("parameter", "Contoso")
         ]);
 
         // Assert
@@ -109,7 +109,7 @@ public void Constructor_SupportsMultiValuedParameters()
         // Arrange and act
         var message = new OpenIddictMessage(
         [
-            new KeyValuePair<string, ImmutableArray<string?>?>("parameter", ["Fabrikam", "Contoso"])
+            KeyValuePair.Create<string, ImmutableArray<string?>>("parameter", ["Fabrikam", "Contoso"])
         ]);
 
         // Assert
@@ -124,7 +124,7 @@ public void Constructor_ExtractsSingleValuedParameters()
         // Arrange and act
         var message = new OpenIddictMessage(
         [
-            new KeyValuePair<string, ImmutableArray<string?>?>("parameter", ["Fabrikam"])
+            KeyValuePair.Create<string, ImmutableArray<string?>>("parameter", ["Fabrikam"])
         ]);
 
         // Assert

diff --git a/...enIddict.Server.AspNetCore.IntegrationTests/OpenIddictServerAspNetCoreIntegrationTests.cs b/...enIddict.Server.AspNetCore.IntegrationTests/OpenIddictServerAspNetCoreIntegrationTests.cs
@@ -823,8 +823,7 @@ void ConfigurePipeline(IApplicationBuilder app)
                     }
 
                     var claims = result.Principal.Claims.GroupBy(claim => claim.Type)
-                        .Select(group => new KeyValuePair<string, ImmutableArray<string?>?>(
-                            group.Key, group.Select(claim => claim.Value).ToImmutableArray<string?>()));
+                        .Select(group => KeyValuePair.Create(group.Key, group.Select(claim => claim.Value).ToImmutableArray<string?>()));
 
                     context.Response.ContentType = "application/json";
                     await context.Response.WriteAsync(JsonSerializer.Serialize(new OpenIddictResponse(claims)));