+ Add spec for handler methods with different visibility in callback_host
! Fix the bug
* Raise custom error when event handler method is missing
Merge branch 'fix/handler-methods-detection' into deploy/spacious

* fix/handler-methods-detection:
  ! Fix the bug
  + Add spec for handler methods with different visibility in callback_host
Merge branch 'feature/raise-error' into deploy/spacious

* feature/raise-error:
  * Raise custom error when event handler method is missing