replace headers with same caseinsensitive key to match http spec

Author: davidgamero

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;
     }
 

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");
+        })
     })
-}
+}