fix: resolve issue where ValueError is not raised if both request and flattened param are set

Author: parthea

gapic/templates/%namespace/%name_%version/%sub/services/%service/_client_macros.j2

@@ -90,7 +90,8 @@
         {% if method.flattened_fields %}
         # - Quick check: If we got a request object, we should *not* have
         #   gotten any keyword arguments that map to the request.
-        has_flattened_params = any([{{ method.flattened_fields.values()|join(", ", attribute="name") }}])
+        flattened_params = [{{ method.flattened_fields.values()|join(", ", attribute="name") }}]
+        has_flattened_params = len([param for param in flattened_params if param is not None]) > 0
         if request is not None and has_flattened_params:
             raise ValueError('If the `request` argument is set, then none of '
                              'the individual field arguments should be set.')

gapic/templates/%namespace/%name_%version/%sub/services/%service/async_client.py.j2

@@ -317,7 +317,8 @@ class {{ service.async_client_name }}:
         {% if method.flattened_fields %}
         # - Quick check: If we got a request object, we should *not* have
         #   gotten any keyword arguments that map to the request.
-        has_flattened_params = any([{{ method.flattened_fields.values()|join(", ", attribute="name") }}])
+        flattened_params = [{{ method.flattened_fields.values()|join(", ", attribute="name") }}]
+        has_flattened_params = len([param for param in flattened_params if param is not None]) > 0
         if request is not None and has_flattened_params:
             raise ValueError("If the `request` argument is set, then none of "
                              "the individual field arguments should be set.")