Genji would find it almost immediately. You can’t really hide anything from him. He’d think it’s adorable, too! He wishes he could still eat candy, but at least he can’t steal yours now, right? Seriously though, he might even help you hide it!
Junkrat wouldn’t even see it unless he sees a shiny candy wrapper. He’d think it’s gold, but nope, just candy. He’d probably take a few… Or a lot… When you’d find out he’d innocently look at you and promises you he’ll steal you more candy.
Lúcio would tease you about it once he found out. He wouldn’t take any, and he’d probably ask. But he’d love how you just had a secret stash. Maybe he won’t even tell you that he knows, just to see you try and add more candy to your stash, or secretly eat a few.
Roadhog would also notice it immediately but I think he’d ignore it. Sure, it was pretty funny but he allowed you to have your privacy. Maybe he’d even add some candy to your stash as a surprise. But really, he wouldn’t mind as long as you didn’t get sick or anything