OnCollision events inside child with collider

Do OnCollision events send inside children of RigidBody? I mean if parent object has RigidBody and it's child has Collider. Child does not recieve OnCollision events. While OnTrigger events send to child. Is it OK? It's not quite clear in documentation. Is it possible to recieve OnCollision inside children of RigidBody? Sample project is in attach. There are two simple cubes for testing collisinons and two for triggers. [Sample project][1] [1]: /storage/temp/25395-oncollision+inside+child+with+collider.zip Thanks