Missing sound Log

log is like this

[12:29:45] [Client thread/INFO]: Setting user: EFRMinecraft
[12:29:45] [Client thread/INFO]: (Session ID is token: :c0c805ff52383ed1990c79a82364120b)
[12:29:47] [Client thread/INFO]: LWJGL Version: 2.9.4
[12:29:47] [Client thread/INFO]: Reloading ResourceManager: Default
[12:29:48] [Client thread/WARN]: Missing sound for event: minecraft:entity.snowman.ambient
[12:29:48] [Client thread/WARN]: Missing sound for event: minecraft:item.bottle.fill_dragonbreath
appears too in 15w50a and 15w49b