[Test Proxy] Correctly support updates to redirection following setting (#35510)

Author: mccoyp

tools/azure-sdk-tools/devtools_testutils/sanitizers.py

@@ -542,10 +542,10 @@ def set_function_recording_options(**kwargs) -> None:
     This must be called during test case execution, rather than at a session, module, or class level. To set recording
     options for all tests, use `set_session_recording_options` instead.
 
-    :keyword bool handle_redirects: The test proxy does not perform transparent follow directs by default. That means
+    :keyword bool handle_redirects: The test proxy performs transparent follow directs by default. That means
         that if the initial request sent through the test proxy results in a 3XX redirect status, the test proxy will
-        not follow. It will return that redirect response to the client and allow it to handle the redirect. Setting
-        `handle_redirects` to True will set the proxy to instead handle redirects itself.
+        follow. Setting `handle_redirects` to False will instead make the test proxy return that redirect response to
+        the client and allow it to handle the redirect.
     :keyword str context_directory: This changes the "root" path that the test proxy uses when loading a recording.
     :keyword certificates: A list of `PemCertificate`s. Any number of certificates is allowed.
     :type certificates: Iterable[PemCertificate]
@@ -564,10 +564,10 @@ def set_session_recording_options(**kwargs) -> None:
     This will set the specified recording options for an entire test session. To set recording options for a single test
     -- which is recommended -- use `set_function_recording_options` instead.
 
-    :keyword bool handle_redirects: The test proxy does not perform transparent follow directs by default. That means
+    :keyword bool handle_redirects: The test proxy performs transparent follow directs by default. That means
         that if the initial request sent through the test proxy results in a 3XX redirect status, the test proxy will
-        not follow. It will return that redirect response to the client and allow it to handle the redirect. Setting
-        `handle_redirects` to True will set the proxy to instead handle redirects itself.
+        follow. Setting `handle_redirects` to False will instead make the test proxy return that redirect response to
+        the client and allow it to handle the redirect.
     :keyword str context_directory: This changes the "root" path that the test proxy uses when loading a recording.
     :keyword certificates: A list of `PemCertificate`s. Any number of certificates is allowed.
     :type certificates: Iterable[PemCertificate]
@@ -703,10 +703,11 @@ def _send_recording_options_request(parameters: Dict, headers: Optional[Dict] =
     if is_live_and_not_recording():
         return
 
-    headers_to_send = {}
-    for key in headers:
-        if headers[key] is not None:
-            headers_to_send[key] = headers[key]
+    headers_to_send = {"Content-Type": "application/json"}
+    if headers:
+        for key in headers:
+            if headers[key] is not None:
+                headers_to_send[key] = headers[key]
 
     http_client = get_http_client()
     http_client.request(
@@ -752,9 +753,10 @@ def _send_sanitizer_request(sanitizer: str, parameters: Dict, headers: Optional[
         return
 
     headers_to_send = {"x-abstraction-identifier": sanitizer, "Content-Type": "application/json"}
-    for key in headers:
-        if headers[key] is not None:
-            headers_to_send[key] = headers[key]
+    if headers:
+        for key in headers:
+            if headers[key] is not None:
+                headers_to_send[key] = headers[key]
 
     http_client = get_http_client()
     http_client.request(
@@ -778,9 +780,10 @@ def _send_transform_request(transform: str, parameters: Dict, headers: Optional[
         return
 
     headers_to_send = {"x-abstraction-identifier": transform, "Content-Type": "application/json"}
-    for key in headers:
-        if headers[key] is not None:
-            headers_to_send[key] = headers[key]
+    if headers:
+        for key in headers:
+            if headers[key] is not None:
+                headers_to_send[key] = headers[key]
 
     http_client = get_http_client()
     http_client.request(