GameAPI#unregisterSpecialItem(SpecialItem): It is no longer possible to unregister built-in types. Use the new register method if you want to replace it
It is now possible to enable the ingame timer (if it was previously turned off) using Arena#setIngameTimeRemaining(timeInSeconds)
Deprecated:
Helper#getPlayerSkinData(Player)
NPCHologramSkin#setSkin(texture, signature)
NPCHologramSkin#getSkinTexture()
NPCHologramSkin#getSkinSignature()
Changes due to "max-nearby-items" now being optionally an expressions: