fix(instrumentation-http): iterating through the OTEL_SEMCONV_STABILITY_OPT_IN content instead of the entry indices (open-telemetry#5137)

Author: omarHassane

experimental/CHANGELOG.md

@@ -50,6 +50,8 @@ All notable changes to experimental packages in this project will be documented
 
 ### :bug: (Bug Fix)
 
+* fix(instrumentation-http): Fix the `OTEL_SEMCONV_STABILITY_OPT_IN` variable check. Using `of` instead of `in` [#5137](https://github.com/open-telemetry/opentelemetry-js/pull/5137)
+
 * fix(instrumentation-http): drop url.parse in favor of URL constructor [#5091](https://github.com/open-telemetry/opentelemetry-js/pull/5091) @pichlermarc
   * fixes a bug where using cyrillic characters in a client request string URL would throw an exception, whereas an un-instrumented client would accept the same input without throwing an exception
 

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

@@ -109,7 +109,7 @@ export class HttpInstrumentation extends InstrumentationBase<HttpInstrumentation
     super('@opentelemetry/instrumentation-http', VERSION, config);
     this._headerCapture = this._createHeaderCapture();
 
-    for (const entry in getEnv().OTEL_SEMCONV_STABILITY_OPT_IN) {
+    for (const entry of getEnv().OTEL_SEMCONV_STABILITY_OPT_IN) {
       if (entry.toLowerCase() === 'http/dup') {
         // http/dup takes highest precedence. If it is found, there is no need to read the rest of the list
         this._semconvStability = SemconvStability.DUPLICATE;