they are not confirmed one yet but i am pretty sure they are. :D
i am pretty sure Law,Garp,Sanji, Miahwk , Dragon , Sabo , Sai , King Elizabello and even Nami are all CoC users , those who showed some lightning , or you could conclude it based on their power levels not a sane person would think that Garp who is DF-less but was Roger's rival didn't have CoC haki. only CoC haki can fill that power gap.