Executors types (#1345)

Signed-off-by: Michael Carlstrom <[email protected]>
Co-authored-by: Tomoya Fujita <[email protected]>

Author: InvincibleRMC

rclpy/rclpy/callback_groups.py

@@ -24,7 +24,8 @@
     from rclpy.service import Service
     from rclpy.waitable import Waitable
     from rclpy.guard_condition import GuardCondition
-    Entity = Union[Subscription, Timer, Client, Service, Waitable[Any], GuardCondition]
+    Entity = Union[Subscription[Any], Timer, Client[Any, Any], Service[Any, Any],
+                   GuardCondition, Waitable[Any]]
 
 
 class CallbackGroup: