From 9670fe99406e4ed8fc05dbb230043281b2a2b033 Mon Sep 17 00:00:00 2001
From: David Gamero <david340804@gmail.com>
Date: Wed, 19 Nov 2025 16:08:27 -0500
Subject: [PATCH 1/5] replace headers with same caseinsensitive key to match
 http spec

---
 .../main/resources/typescript/http/http.mustache    |  7 +++++++
 .../default/test/http/isomorphic-fetch.test.ts      | 13 ++++++++++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/modules/openapi-generator/src/main/resources/typescript/http/http.mustache b/modules/openapi-generator/src/main/resources/typescript/http/http.mustache
index 67ff4139aee1..4c10a93a9ba7 100644
--- a/modules/openapi-generator/src/main/resources/typescript/http/http.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript/http/http.mustache
@@ -183,6 +183,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts b/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts
index 748c7ad46e33..a08f785bd9a9 100644
--- a/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts
+++ b/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts
@@ -67,5 +67,16 @@ for (let libName in libs) {
                     done();
             }).catch(done)
         })
+        
+        it("Case Insensitive Header Replacement", (done) => {
+            let requestContext = new petstore.RequestContext("http://httpbin.org/cookies", petstore.HttpMethod.GET);
+            requestContext.setHeaderParam("testkey1":"testvalue1");
+            expect(requestContext.getHeaders().testkey1).to.eq("testvalue1");
+
+            // replace with differently cased key
+            requestContext.setHeaderParam("tEsTkeY1":"testvalue2");
+            expect(requestContext.getHeaders().testkey1).to.be.undefined;
+            expect(requestContext.getHeaders().testkey1).to.eq("testvalue2");
+        })
     })
-}
\ No newline at end of file
+}

From cd02b04d6b6d131e2207e4667e2e0952c44e0262 Mon Sep 17 00:00:00 2001
From: David Gamero <david340804@gmail.com>
Date: Wed, 19 Nov 2025 16:27:08 -0500
Subject: [PATCH 2/5] regenerate samples

---
 samples/client/echo_api/typescript/build/http/http.ts      | 7 +++++++
 .../others/typescript/builds/array-of-lists/http/http.ts   | 7 +++++++
 .../typescript/builds/enum-single-value/http/http.ts       | 7 +++++++
 .../typescript/builds/null-types-simple/http/http.ts       | 7 +++++++
 .../typescript/builds/with-unique-items/http/http.ts       | 7 +++++++
 .../others/typescript/encode-decode/build/http/http.ts     | 7 +++++++
 .../client/petstore/typescript/builds/browser/http/http.ts | 7 +++++++
 .../typescript/builds/composed-schemas/http/http.ts        | 7 +++++++
 .../client/petstore/typescript/builds/default/http/http.ts | 7 +++++++
 .../client/petstore/typescript/builds/deno/http/http.ts    | 7 +++++++
 .../typescript/builds/deno_object_params/http/http.ts      | 7 +++++++
 .../petstore/typescript/builds/explode-query/http/http.ts  | 7 +++++++
 .../petstore/typescript/builds/inversify/http/http.ts      | 7 +++++++
 .../client/petstore/typescript/builds/jquery/http/http.ts  | 7 +++++++
 .../petstore/typescript/builds/nullable-enum/http/http.ts  | 7 +++++++
 .../petstore/typescript/builds/object_params/http/http.ts  | 7 +++++++
 16 files changed, 112 insertions(+)

diff --git a/samples/client/echo_api/typescript/build/http/http.ts b/samples/client/echo_api/typescript/build/http/http.ts
index 7eaf00563272..82d21a50a254 100644
--- a/samples/client/echo_api/typescript/build/http/http.ts
+++ b/samples/client/echo_api/typescript/build/http/http.ts
@@ -133,6 +133,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/client/others/typescript/builds/array-of-lists/http/http.ts b/samples/client/others/typescript/builds/array-of-lists/http/http.ts
index d48cbd6b7705..3e8ffdb4cd13 100644
--- a/samples/client/others/typescript/builds/array-of-lists/http/http.ts
+++ b/samples/client/others/typescript/builds/array-of-lists/http/http.ts
@@ -124,6 +124,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/client/others/typescript/builds/enum-single-value/http/http.ts b/samples/client/others/typescript/builds/enum-single-value/http/http.ts
index d48cbd6b7705..3e8ffdb4cd13 100644
--- a/samples/client/others/typescript/builds/enum-single-value/http/http.ts
+++ b/samples/client/others/typescript/builds/enum-single-value/http/http.ts
@@ -124,6 +124,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/client/others/typescript/builds/null-types-simple/http/http.ts b/samples/client/others/typescript/builds/null-types-simple/http/http.ts
index d48cbd6b7705..3e8ffdb4cd13 100644
--- a/samples/client/others/typescript/builds/null-types-simple/http/http.ts
+++ b/samples/client/others/typescript/builds/null-types-simple/http/http.ts
@@ -124,6 +124,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/client/others/typescript/builds/with-unique-items/http/http.ts b/samples/client/others/typescript/builds/with-unique-items/http/http.ts
index d48cbd6b7705..3e8ffdb4cd13 100644
--- a/samples/client/others/typescript/builds/with-unique-items/http/http.ts
+++ b/samples/client/others/typescript/builds/with-unique-items/http/http.ts
@@ -124,6 +124,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/client/others/typescript/encode-decode/build/http/http.ts b/samples/client/others/typescript/encode-decode/build/http/http.ts
index 7eaf00563272..82d21a50a254 100644
--- a/samples/client/others/typescript/encode-decode/build/http/http.ts
+++ b/samples/client/others/typescript/encode-decode/build/http/http.ts
@@ -133,6 +133,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/openapi3/client/petstore/typescript/builds/browser/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/browser/http/http.ts
index d48cbd6b7705..3e8ffdb4cd13 100644
--- a/samples/openapi3/client/petstore/typescript/builds/browser/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/browser/http/http.ts
@@ -124,6 +124,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/openapi3/client/petstore/typescript/builds/composed-schemas/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/composed-schemas/http/http.ts
index d48cbd6b7705..3e8ffdb4cd13 100644
--- a/samples/openapi3/client/petstore/typescript/builds/composed-schemas/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/composed-schemas/http/http.ts
@@ -124,6 +124,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/openapi3/client/petstore/typescript/builds/default/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/default/http/http.ts
index 7eaf00563272..82d21a50a254 100644
--- a/samples/openapi3/client/petstore/typescript/builds/default/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/default/http/http.ts
@@ -133,6 +133,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/openapi3/client/petstore/typescript/builds/deno/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/deno/http/http.ts
index 0b57a8a07b1b..830208d1a3d3 100644
--- a/samples/openapi3/client/petstore/typescript/builds/deno/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/deno/http/http.ts
@@ -123,6 +123,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/openapi3/client/petstore/typescript/builds/deno_object_params/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/deno_object_params/http/http.ts
index 0b57a8a07b1b..830208d1a3d3 100644
--- a/samples/openapi3/client/petstore/typescript/builds/deno_object_params/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/deno_object_params/http/http.ts
@@ -123,6 +123,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/openapi3/client/petstore/typescript/builds/explode-query/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/explode-query/http/http.ts
index 7eaf00563272..82d21a50a254 100644
--- a/samples/openapi3/client/petstore/typescript/builds/explode-query/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/explode-query/http/http.ts
@@ -133,6 +133,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/openapi3/client/petstore/typescript/builds/inversify/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/inversify/http/http.ts
index e96c984cb800..9c0dfcdf821d 100644
--- a/samples/openapi3/client/petstore/typescript/builds/inversify/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/inversify/http/http.ts
@@ -133,6 +133,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/openapi3/client/petstore/typescript/builds/jquery/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/jquery/http/http.ts
index 0fb26e3bb3f8..56e945c80d3b 100644
--- a/samples/openapi3/client/petstore/typescript/builds/jquery/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/jquery/http/http.ts
@@ -124,6 +124,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/openapi3/client/petstore/typescript/builds/nullable-enum/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/nullable-enum/http/http.ts
index d48cbd6b7705..3e8ffdb4cd13 100644
--- a/samples/openapi3/client/petstore/typescript/builds/nullable-enum/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/nullable-enum/http/http.ts
@@ -124,6 +124,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 
diff --git a/samples/openapi3/client/petstore/typescript/builds/object_params/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/object_params/http/http.ts
index 7eaf00563272..82d21a50a254 100644
--- a/samples/openapi3/client/petstore/typescript/builds/object_params/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/object_params/http/http.ts
@@ -133,6 +133,13 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
+        // Delete any existing headers with case-insensitive matching
+        const lowerKey = key.toLowerCase();
+        for (const existingKey in this.headers) {
+            if (existingKey.toLowerCase() === lowerKey) {
+                delete this.headers[existingKey];
+            }
+        }
         this.headers[key] = value;
     }
 

From 7e059eee7f9e8132be658572c3141c2e2d2f9b79 Mon Sep 17 00:00:00 2001
From: David Gamero <david340804@gmail.com>
Date: Wed, 19 Nov 2025 16:40:44 -0500
Subject: [PATCH 3/5] regenerate samples

---
 .../src/main/resources/typescript/http/http.mustache            | 2 +-
 samples/client/echo_api/typescript/build/http/http.ts           | 2 +-
 .../client/others/typescript/builds/array-of-lists/http/http.ts | 2 +-
 .../others/typescript/builds/enum-single-value/http/http.ts     | 2 +-
 .../others/typescript/builds/null-types-simple/http/http.ts     | 2 +-
 .../others/typescript/builds/with-unique-items/http/http.ts     | 2 +-
 .../client/others/typescript/encode-decode/build/http/http.ts   | 2 +-
 .../client/petstore/typescript/builds/browser/http/http.ts      | 2 +-
 .../petstore/typescript/builds/composed-schemas/http/http.ts    | 2 +-
 .../client/petstore/typescript/builds/default/http/http.ts      | 2 +-
 .../client/petstore/typescript/builds/deno/http/http.ts         | 2 +-
 .../petstore/typescript/builds/deno_object_params/http/http.ts  | 2 +-
 .../petstore/typescript/builds/explode-query/http/http.ts       | 2 +-
 .../client/petstore/typescript/builds/inversify/http/http.ts    | 2 +-
 .../client/petstore/typescript/builds/jquery/http/http.ts       | 2 +-
 .../petstore/typescript/builds/nullable-enum/http/http.ts       | 2 +-
 .../petstore/typescript/builds/object_params/http/http.ts       | 2 +-
 .../typescript/tests/default/test/http/isomorphic-fetch.test.ts | 2 +-
 18 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/modules/openapi-generator/src/main/resources/typescript/http/http.mustache b/modules/openapi-generator/src/main/resources/typescript/http/http.mustache
index 4c10a93a9ba7..6dc521f7ccc6 100644
--- a/modules/openapi-generator/src/main/resources/typescript/http/http.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript/http/http.mustache
@@ -183,7 +183,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/client/echo_api/typescript/build/http/http.ts b/samples/client/echo_api/typescript/build/http/http.ts
index 82d21a50a254..a5f59b18c70f 100644
--- a/samples/client/echo_api/typescript/build/http/http.ts
+++ b/samples/client/echo_api/typescript/build/http/http.ts
@@ -133,7 +133,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/client/others/typescript/builds/array-of-lists/http/http.ts b/samples/client/others/typescript/builds/array-of-lists/http/http.ts
index 3e8ffdb4cd13..6ac932c7c23a 100644
--- a/samples/client/others/typescript/builds/array-of-lists/http/http.ts
+++ b/samples/client/others/typescript/builds/array-of-lists/http/http.ts
@@ -124,7 +124,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/client/others/typescript/builds/enum-single-value/http/http.ts b/samples/client/others/typescript/builds/enum-single-value/http/http.ts
index 3e8ffdb4cd13..6ac932c7c23a 100644
--- a/samples/client/others/typescript/builds/enum-single-value/http/http.ts
+++ b/samples/client/others/typescript/builds/enum-single-value/http/http.ts
@@ -124,7 +124,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/client/others/typescript/builds/null-types-simple/http/http.ts b/samples/client/others/typescript/builds/null-types-simple/http/http.ts
index 3e8ffdb4cd13..6ac932c7c23a 100644
--- a/samples/client/others/typescript/builds/null-types-simple/http/http.ts
+++ b/samples/client/others/typescript/builds/null-types-simple/http/http.ts
@@ -124,7 +124,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/client/others/typescript/builds/with-unique-items/http/http.ts b/samples/client/others/typescript/builds/with-unique-items/http/http.ts
index 3e8ffdb4cd13..6ac932c7c23a 100644
--- a/samples/client/others/typescript/builds/with-unique-items/http/http.ts
+++ b/samples/client/others/typescript/builds/with-unique-items/http/http.ts
@@ -124,7 +124,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/client/others/typescript/encode-decode/build/http/http.ts b/samples/client/others/typescript/encode-decode/build/http/http.ts
index 82d21a50a254..a5f59b18c70f 100644
--- a/samples/client/others/typescript/encode-decode/build/http/http.ts
+++ b/samples/client/others/typescript/encode-decode/build/http/http.ts
@@ -133,7 +133,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/openapi3/client/petstore/typescript/builds/browser/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/browser/http/http.ts
index 3e8ffdb4cd13..6ac932c7c23a 100644
--- a/samples/openapi3/client/petstore/typescript/builds/browser/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/browser/http/http.ts
@@ -124,7 +124,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/openapi3/client/petstore/typescript/builds/composed-schemas/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/composed-schemas/http/http.ts
index 3e8ffdb4cd13..6ac932c7c23a 100644
--- a/samples/openapi3/client/petstore/typescript/builds/composed-schemas/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/composed-schemas/http/http.ts
@@ -124,7 +124,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/openapi3/client/petstore/typescript/builds/default/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/default/http/http.ts
index 82d21a50a254..a5f59b18c70f 100644
--- a/samples/openapi3/client/petstore/typescript/builds/default/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/default/http/http.ts
@@ -133,7 +133,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/openapi3/client/petstore/typescript/builds/deno/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/deno/http/http.ts
index 830208d1a3d3..c71b19bf2895 100644
--- a/samples/openapi3/client/petstore/typescript/builds/deno/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/deno/http/http.ts
@@ -123,7 +123,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/openapi3/client/petstore/typescript/builds/deno_object_params/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/deno_object_params/http/http.ts
index 830208d1a3d3..c71b19bf2895 100644
--- a/samples/openapi3/client/petstore/typescript/builds/deno_object_params/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/deno_object_params/http/http.ts
@@ -123,7 +123,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/openapi3/client/petstore/typescript/builds/explode-query/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/explode-query/http/http.ts
index 82d21a50a254..a5f59b18c70f 100644
--- a/samples/openapi3/client/petstore/typescript/builds/explode-query/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/explode-query/http/http.ts
@@ -133,7 +133,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/openapi3/client/petstore/typescript/builds/inversify/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/inversify/http/http.ts
index 9c0dfcdf821d..b2c101e5f228 100644
--- a/samples/openapi3/client/petstore/typescript/builds/inversify/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/inversify/http/http.ts
@@ -133,7 +133,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/openapi3/client/petstore/typescript/builds/jquery/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/jquery/http/http.ts
index 56e945c80d3b..db24c4927063 100644
--- a/samples/openapi3/client/petstore/typescript/builds/jquery/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/jquery/http/http.ts
@@ -124,7 +124,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/openapi3/client/petstore/typescript/builds/nullable-enum/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/nullable-enum/http/http.ts
index 3e8ffdb4cd13..6ac932c7c23a 100644
--- a/samples/openapi3/client/petstore/typescript/builds/nullable-enum/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/nullable-enum/http/http.ts
@@ -124,7 +124,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/openapi3/client/petstore/typescript/builds/object_params/http/http.ts b/samples/openapi3/client/petstore/typescript/builds/object_params/http/http.ts
index 82d21a50a254..a5f59b18c70f 100644
--- a/samples/openapi3/client/petstore/typescript/builds/object_params/http/http.ts
+++ b/samples/openapi3/client/petstore/typescript/builds/object_params/http/http.ts
@@ -133,7 +133,7 @@ export class RequestContext {
     }
 
     public setHeaderParam(key: string, value: string): void  {
-        // Delete any existing headers with case-insensitive matching
+        // Delete any existing headers with case-insensitive matching keys
         const lowerKey = key.toLowerCase();
         for (const existingKey in this.headers) {
             if (existingKey.toLowerCase() === lowerKey) {
diff --git a/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts b/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts
index a08f785bd9a9..cd7e446a8a45 100644
--- a/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts
+++ b/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts
@@ -76,7 +76,7 @@ for (let libName in libs) {
             // replace with differently cased key
             requestContext.setHeaderParam("tEsTkeY1":"testvalue2");
             expect(requestContext.getHeaders().testkey1).to.be.undefined;
-            expect(requestContext.getHeaders().testkey1).to.eq("testvalue2");
+            expect(requestContext.getHeaders().tEsTkeY1).to.eq("testvalue2");
         })
     })
 }

From dee493e8aaa29ba0b131eb960892f3aed5411fbf Mon Sep 17 00:00:00 2001
From: David Gamero <david340804@gmail.com>
Date: Thu, 20 Nov 2025 17:42:54 -0500
Subject: [PATCH 4/5] enable test for header case-insensitive replacement

---
 .../test/http/isomorphic-fetch.test.ts        | 21 ++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts b/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts
index cd7e446a8a45..9129cfca1a03 100644
--- a/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts
+++ b/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts
@@ -68,15 +68,30 @@ for (let libName in libs) {
             }).catch(done)
         })
         
-        it("Case Insensitive Header Replacement", (done) => {
+    })
+    describe("Header Case Sensitivity", () => {
+        it("different case header key is replaced", () => {
             let requestContext = new petstore.RequestContext("http://httpbin.org/cookies", petstore.HttpMethod.GET);
-            requestContext.setHeaderParam("testkey1":"testvalue1");
+            expect(requestContext.getHeaders().testkey1).to.be.undefined;
+
+            requestContext.setHeaderParam("testkey1","testvalue1");
             expect(requestContext.getHeaders().testkey1).to.eq("testvalue1");
 
             // replace with differently cased key
-            requestContext.setHeaderParam("tEsTkeY1":"testvalue2");
+            requestContext.setHeaderParam("tEsTkeY1","testvalue2");
             expect(requestContext.getHeaders().testkey1).to.be.undefined;
             expect(requestContext.getHeaders().tEsTkeY1).to.eq("testvalue2");
         })
+        it("indentical header key writes replace content", () => {
+            let requestContext = new petstore.RequestContext("http://httpbin.org/cookies", petstore.HttpMethod.GET);
+            expect(requestContext.getHeaders().testkey1).to.be.undefined;
+
+            requestContext.setHeaderParam("testkey1","testvalue1");
+            expect(requestContext.getHeaders().testkey1).to.eq("testvalue1");
+
+            // replace with differently cased key
+            requestContext.setHeaderParam("testkey1","testvalue2");
+            expect(requestContext.getHeaders().testkey1).to.eq("testvalue2");
+        })
     })
 }

From 87fc74eb4e9dbf9dce480e10e2ccfbfcf320830d Mon Sep 17 00:00:00 2001
From: David Gamero <david340804@gmail.com>
Date: Thu, 20 Nov 2025 17:50:21 -0500
Subject: [PATCH 5/5] reduce redundant test comments

---
 .../typescript/tests/default/test/http/isomorphic-fetch.test.ts | 2 --
 1 file changed, 2 deletions(-)

diff --git a/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts b/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts
index 9129cfca1a03..a99e4c652672 100644
--- a/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts
+++ b/samples/openapi3/client/petstore/typescript/tests/default/test/http/isomorphic-fetch.test.ts
@@ -77,7 +77,6 @@ for (let libName in libs) {
             requestContext.setHeaderParam("testkey1","testvalue1");
             expect(requestContext.getHeaders().testkey1).to.eq("testvalue1");
 
-            // replace with differently cased key
             requestContext.setHeaderParam("tEsTkeY1","testvalue2");
             expect(requestContext.getHeaders().testkey1).to.be.undefined;
             expect(requestContext.getHeaders().tEsTkeY1).to.eq("testvalue2");
@@ -89,7 +88,6 @@ for (let libName in libs) {
             requestContext.setHeaderParam("testkey1","testvalue1");
             expect(requestContext.getHeaders().testkey1).to.eq("testvalue1");
 
-            // replace with differently cased key
             requestContext.setHeaderParam("testkey1","testvalue2");
             expect(requestContext.getHeaders().testkey1).to.eq("testvalue2");
         })