Revert "api_core: Make PageIterator.item_to_value public. (#4702)" (#4731)

Author: Jon Wayne Parrott

packages/google-cloud-spanner/google/cloud/spanner_v1/client.py

@@ -205,7 +205,7 @@ def list_instance_configs(self, page_size=None, page_token=None):
         page_iter = self.instance_admin_api.list_instance_configs(
             path, page_size=page_size, metadata=metadata)
         page_iter.next_page_token = page_token
-        page_iter.item_to_value = _item_to_instance_config
+        page_iter._item_to_value = _item_to_instance_config
         return page_iter
 
     def instance(self, instance_id,
@@ -265,7 +265,7 @@ def list_instances(self, filter_='', page_size=None, page_token=None):
         path = 'projects/%s' % (self.project,)
         page_iter = self.instance_admin_api.list_instances(
             path, page_size=page_size, metadata=metadata)
-        page_iter.item_to_value = self._item_to_instance
+        page_iter._item_to_value = self._item_to_instance
         page_iter.next_page_token = page_token
         return page_iter
 

packages/google-cloud-spanner/google/cloud/spanner_v1/instance.py

@@ -349,7 +349,7 @@ def list_databases(self, page_size=None, page_token=None):
         page_iter = self._client.database_admin_api.list_databases(
             self.name, page_size=page_size, metadata=metadata)
         page_iter.next_page_token = page_token
-        page_iter.item_to_value = self._item_to_database
+        page_iter._item_to_value = self._item_to_database
         return page_iter
 
     def _item_to_database(self, iterator, database_pb):