When I create a Mecanim object for Spine animation it would create a AnimationController object. When I click expand arrow on it, it would list all AnimationClips referenced to that object. I wonder how I can access those objects from code? I noticed AnimationController have a AnimationClips collection but it is empty.
Found it! In case someone else needs it:
AssetDatabase.LoadAllAssetsAtPath("Assets/{PATH_TO_CONTROLLER_FILE}.controller")