FIX: Ensure callback delegates are created for ActionMaps added after an asset has already assigned to PlayerInput component (case ISXB-711)

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -30,6 +30,7 @@ however, it has to be formatted properly to pass verification tests.
 - Fixed tooltip support in the UI Toolkit version of the Input Actions Asset editor.
 - Fixed documentation to clarify bindings with modifiers `overrideModifiersNeedToBePressedFirst` configuration [ISXB-806](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-806).
 - Fixed an issue in `Samples/Visualizers/GamepadVisualizer.unity` sample where the visualization wouldn't handle device disconnects or current device changes properly (ISXB-1243).
+- Fixed an issue where action map delegates were not updated when the asset already assigned to the PlayerInput component were changed [ISXB-711](https://issuetracker.unity3d.com/product/unity/issues/guid/ISXB-711).
 
 ### Changed
 - Added back the InputManager to InputSystem project-wide asset migration code with performance improvement (ISX-2086).

Packages/com.unity.inputsystem/InputSystem/Plugins/PlayerInput/PlayerInput.cs

@@ -950,6 +950,8 @@ public TDevice GetDevice<TDevice>()
         /// </example>
         public void ActivateInput()
         {
+            UpdateDelegates();
+
             m_InputActive = true;
 
             // If we have no current action map but there's a default
@@ -960,6 +962,31 @@ public void ActivateInput()
                 m_CurrentActionMap?.Enable();
         }
 
+        // Users can add and remove actions maps *after* assigning an InputActionAsset to the PlayerInput component.
+        // This ensures "actionTriggered" delegates are assigned for new maps (case isxb-711)
+        //
+        private int m_AllMapsHashCode = 0;
+        private void UpdateDelegates()
+        {
+            if (m_Actions == null)
+            {
+                m_AllMapsHashCode = 0;
+                return;
+            }
+
+            int allMapsHashCode = 0;
+            foreach (var actionMap in m_Actions.actionMaps)
+            {
+                allMapsHashCode ^= actionMap.GetHashCode();
+            }
+            if (m_AllMapsHashCode != allMapsHashCode)
+            {
+                InstallOnActionTriggeredHook();
+                CacheMessageNames();
+                m_AllMapsHashCode = allMapsHashCode;
+            }
+        }
+
         /// <summary>
         /// Disable input on the player, by disabling the current action map
         /// </summary>
@@ -1515,6 +1542,8 @@ private void CacheMessageNames()
 
         private void ClearCaches()
         {
+            if (m_ActionMessageNames != null)
+                m_ActionMessageNames.Clear();
         }
 
         /// <summary>