support empty headers

Author: daniel-sanche

google/cloud/bigtable_v2/services/bigtable/async_client.py

@@ -1496,7 +1496,8 @@ def execute_query(
         if regex_match and regex_match.group("name"):
             header_params["name"] = regex_match.group("name")
 
-        if request.app_profile_id:
+        if request.app_profile_id is not None:
+            # execute_query currently requires empty header support. TODO: remove after support is added
             header_params["app_profile_id"] = request.app_profile_id
 
         if header_params:

google/cloud/bigtable_v2/services/bigtable/client.py

@@ -1893,7 +1893,8 @@ def execute_query(
         if regex_match and regex_match.group("name"):
             header_params["name"] = regex_match.group("name")
 
-        if request.app_profile_id:
+        if request.app_profile_id is not None:
+            # execute_query currently requires empty header support. TODO: remove after support is adde
             header_params["app_profile_id"] = request.app_profile_id
 
         if header_params: