Use _get_serializer() in _get_operation_id()

Also, capitalize `list` action to be in sync with `method_mapping`

rest_framework/schemas/openapi.py

@@ -105,7 +105,7 @@ def _get_operation_id(self, path, method):
         """
         method_name = getattr(self.view, 'action', method.lower())
         if is_list_view(path, method, self.view):
-            action = 'list'
+            action = 'List'
         elif method_name not in self.method_mapping:
             action = method_name
         else:
@@ -117,8 +117,8 @@ def _get_operation_id(self, path, method):
             name = model.__name__
 
         # Try with the serializer class name
-        elif hasattr(self.view, 'get_serializer_class'):
-            name = self.view.get_serializer_class().__name__
+        elif self._get_serializer(path, method) is not None:
+            name = self._get_serializer(path, method).__class__.__name__
             if name.endswith('Serializer'):
                 name = name[:-10]
 
@@ -135,7 +135,7 @@ def _get_operation_id(self, path, method):
             if name.endswith(action.title()):  # ListView, UpdateAPIView, ThingDelete ...
                 name = name[:-len(action)]
 
-        if action == 'list' and not name.endswith('s'):  # listThings instead of listThing
+        if action == 'List' and not name.endswith('s'):  # listThings instead of listThing
             name += 's'
 
         return action + name