fix: requests headers none argument fix (open-telemetry#708)

Author: HiveTraum

ext/opentelemetry-ext-requests/src/opentelemetry/ext/requests/__init__.py

@@ -96,8 +96,9 @@ def instrumented_request(self, method, url, *args, **kwargs):
             span.set_attribute("http.method", method.upper())
             span.set_attribute("http.url", url)
 
-            headers = kwargs.setdefault("headers", {})
+            headers = kwargs.get("headers", {}) or {}
             propagators.inject(type(headers).__setitem__, headers)
+            kwargs["headers"] = headers
 
             try:
                 result = wrapped(

ext/opentelemetry-ext-requests/tests/test_requests_integration.py

@@ -228,6 +228,10 @@ def test_custom_tracer_provider(self):
 
         self.assertIs(span.resource, resource)
 
+    def test_if_headers_equals_none(self):
+        result = requests.get(self.URL, headers=None)
+        self.assertEqual(result.text, "Hello!")
+
     @mock.patch("requests.Session.send", side_effect=requests.RequestException)
     def test_requests_exception_without_response(self, *_, **__):