Found this on reddit.
Edit: Please go post on the bug report to get some attention from Blizzard. We really need this fixed before the season starts. Confirmed abilities breaking Stealth in PvP - #2 by Jo-moon-guard
---- Update - Formatted List ----
Confirmed Bugged:
Warlock - Malevolence - 100 yard range AoE stealth break ignoring line of sight.
Warlock - Any shard spenders (Hellcaller hero talent) - 100 yard range AoE stealth break ignoring line of sight. Basically spammable.
Paladin - Divine Resonance (Divine Toll) - Automatic Judgment knocks you out of stealth even while not visible. It appears the range check is what breaks you out of stealth, no hammer is ever thrown at you. Range is limited to 30 yards and line of sight, but knocks you out of stealth regardless of what direction the Paladin is facing.
Frost Mage Splinterstorm - Frost Splinter / Embedded Frost Splinter hit stealthed targets within 20 yards of the mage casting.
Not Bugged:
Monk - Keg Smash - Knocks you out if you're in range of the target that is hit - roughly 8-10 yards.
Warlock - Shared Fate - Damage pulse will knock you out if you are in range of the target being hit - roughly 10 yards.
Ice Lance AoE / Living Bomb from Frostfire Empowerment