Minecraft wiki entry for JSON_format, associated text:  conditions:
 victims: The victims hit by the lightning summoned by the Channeling enchantment. All entities in this list must be hit. Each entry may also be a list of predicates that must pass in order for the trigger to activate. The checks are applied to the victim hit by the enchanted trident.
: A victim.
All possible conditions for entities[show]
 player: The player that would get the advancement. May also be a list of predicates that must pass in order for the trigger to activate.
All possible conditions for entities[show]