Whether or not this Collider generates contacts for Physics.ContactEvent.
If this property is set to true, all contacts produced by this collider will appear in the buffer. If this property is set to false, contact generation will depend on these factors:
If the Collider or its Rigidbody have a script with a MonoBehaviour.OnCollisionStay method, all contacts will be generated for Physics.ContactEvent.
If the Collider or its Rigidbody has a script with either MonoBehaviour.OnCollisionEnter or MonoBehaviour.OnCollisionExit but not MonoBehaviour.OnCollisionStay, enter and exit contacts will be generated for Physics.ContactEvent, but not stay contacts.
If the PhysicsVisualizationSettings.showAllContacts property is set to true, all Colliders will generate all contacts for visualisation purposes!