fix(http): remove outgoing headers normalization

experimental/CHANGELOG.md

@@ -14,6 +14,7 @@ All notable changes to experimental packages in this project will be documented
   * Fixes an error where the generated JS files were not included in the esnext package due to a failure of the tsconfig generation
 * fix(sdk-node): register instrumentations early [#3502](https://github.com/open-telemetry/opentelemetry-js/pull/3502) @flarna
 * fix: include tracestate in export [#3569](https://github.com/open-telemetry/opentelemetry-js/pull/3569) @flarna
+* fix(http) Remove outgoing headers normalization [#3557](https://github.com/open-telemetry/opentelemetry-js/pull/3557) @marcinjahn
 
 ### :books: (Refine Doc)
 

experimental/packages/opentelemetry-instrumentation-http/src/utils.ts

@@ -276,14 +276,6 @@ export const getRequestInfo = (
     origin = `${optionsParsed.protocol || 'http:'}//${hostname}`;
   }
 
-  const headers = optionsParsed.headers ?? {};
-  optionsParsed.headers = Object.keys(headers).reduce(
-    (normalizedHeader, key) => {
-      normalizedHeader[key.toLowerCase()] = headers[key];
-      return normalizedHeader;
-    },
-    {} as OutgoingHttpHeaders
-  );
   // some packages return method in lowercase..
   // ensure upperCase for consistency
   const method = optionsParsed.method

experimental/packages/opentelemetry-instrumentation-http/test/functionals/http-enable.test.ts

@@ -508,11 +508,6 @@ describe('HttpInstrumentation', () => {
               'user-agent': testValue,
             },
           }),
-          httpRequest.get(`${protocol}://${hostname}:${serverPort}`, {
-            headers: {
-              'uSeR-aGeNt': testValue,
-            },
-          }),
         ]);
         const spans = memoryExporter.getFinishedSpans();
         assert.strictEqual(spans.length, 0);

experimental/packages/opentelemetry-instrumentation-http/test/functionals/https-enable.test.ts

@@ -460,11 +460,6 @@ describe('HttpsInstrumentation', () => {
               'user-agent': testValue,
             },
           }),
-          httpsRequest.get(`${protocol}://${hostname}:${serverPort}`, {
-            headers: {
-              'uSeR-aGeNt': testValue,
-            },
-          }),
         ]);
         const spans = memoryExporter.getFinishedSpans();
         assert.strictEqual(spans.length, 0);