The LivingEntity interface is lacking a method to retrieve an active PotionEffect directly by its PotionEffectType. This is otherwise only achievable by matching the PotionEffectType of the PotionEffects returned by the LivingEntity#getActivePotionEffects method, which in inconvenient, and less efficient than getting the PotionEffect directly.

Some applicable purposes of this is updating a player according to their active PotionEffects.