Steps to reproduce:
1. Create a project
2. Add a Sprite in the Hierarchy
3. Add a CompositeCollider2D to the Sprite
4. Add a BoxCollider2D to the Sprite
5. Check Used by Effector in the BoxCollider2D component
6. Observe the warning:
This collider will not function with effector until there is at least one enabled 2D effector on this GameObject
7. Check Used by Composite in the BoxCollider2D component
8. Observe, the warning did not disappear

Expected result: Warning should disappear
Actual result: Inspector shows the warning

Reproduced with: 5.6.0p1, 5.6.0p4, 2017.1.0b4