From 71c9734d5bc0c2b329e7a7980c798645fd29ed8a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?K=C3=A9vin=20Chalet?= <kevinchalet@gmail.com>
Date: Mon, 6 Jul 2026 15:56:54 +0200
Subject: [PATCH] Optimize the creation of OpenIddictMessage instances

---
 .../Primitives/OpenIddictMessage.cs           | 29 ++++++++-----------
 .../Primitives/OpenIddictMessageTests.cs      |  2 +-
 2 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/src/OpenIddict.Abstractions/Primitives/OpenIddictMessage.cs b/src/OpenIddict.Abstractions/Primitives/OpenIddictMessage.cs
index d48dbe52..50c14c0b 100644
--- a/src/OpenIddict.Abstractions/Primitives/OpenIddictMessage.cs
+++ b/src/OpenIddict.Abstractions/Primitives/OpenIddictMessage.cs
@@ -59,12 +59,7 @@ public class OpenIddictMessage
 
             // While generally discouraged, JSON objects can contain multiple properties with
             // the same name. In this case, the last occurrence replaces the previous ones.
-            if (HasParameter(parameter.Name))
-            {
-                RemoveParameter(parameter.Name);
-            }
-
-            AddParameter(parameter.Name, parameter.Value);
+            Parameters[parameter.Name] = parameter.Value;
         }
     }
 
@@ -87,12 +82,7 @@ public class OpenIddictMessage
 
             // While generally discouraged, JSON objects can contain multiple properties with
             // the same name. In this case, the last occurrence replaces the previous ones.
-            if (HasParameter(parameter.Key))
-            {
-                RemoveParameter(parameter.Key);
-            }
-
-            AddParameter(parameter.Key, parameter.Value);
+            Parameters[parameter.Key] = parameter.Value;
         }
     }
 
@@ -113,7 +103,12 @@ public class OpenIddictMessage
                 continue;
             }
 
-            AddParameter(parameter.Key, parameter.Value);
+            if (Parameters.ContainsKey(parameter.Key))
+            {
+                throw new ArgumentException(SR.GetResourceString(SR.ID0191), nameof(parameters));
+            }
+
+            Parameters.Add(parameter.Key, parameter.Value);
         }
     }
 
@@ -138,7 +133,7 @@ public class OpenIddictMessage
             // 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.Select(parameter => parameter.Value).ToArray() switch
+            Parameters.Add(parameter.Key, parameter.Select(parameter => parameter.Value).ToArray() switch
             {
                       []       => default,
                 [string value] => new OpenIddictParameter(value),
@@ -168,7 +163,7 @@ public class OpenIddictMessage
             // 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
+            Parameters.Add(parameter.Key, parameter.Value switch
             {
                 { IsDefaultOrEmpty: true } => default,
                       [string value]       => new OpenIddictParameter(value),
@@ -229,7 +224,7 @@ public class OpenIddictMessage
             // 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
+            Parameters.Add(parameter.Key, parameter.Value switch
             {
                       []       => default,
                 [string value] => new OpenIddictParameter(value),
@@ -260,7 +255,7 @@ public class OpenIddictMessage
             // 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(name, parameters.GetValues(name) switch
+            Parameters.Add(name, parameters.GetValues(name) switch
             {
                   null or []   => default,
                 [string value] => new OpenIddictParameter(value),
diff --git a/test/OpenIddict.Abstractions.Tests/Primitives/OpenIddictMessageTests.cs b/test/OpenIddict.Abstractions.Tests/Primitives/OpenIddictMessageTests.cs
index 05ee45ec..83e5e816 100644
--- a/test/OpenIddict.Abstractions.Tests/Primitives/OpenIddictMessageTests.cs
+++ b/test/OpenIddict.Abstractions.Tests/Primitives/OpenIddictMessageTests.cs
@@ -41,7 +41,7 @@ public class OpenIddictMessageTests
             ]);
         });
 
-        Assert.Equal("name", exception.ParamName);
+        Assert.Equal("parameters", exception.ParamName);
         Assert.StartsWith(SR.GetResourceString(SR.ID0191), exception.Message);
     }