The entity components documentation describes a component, minecraft:on_hurt, and the vanilla behavior json for blazes, pillagers, and end crystals contain this component. However, this component does not do anything.

Steps to reproduce

1. Load Test pack for on_hurt.mcpack. This pack removes the component "minecraft:on_hurt_by_player" from blazes, and adds the component "minecraft:on_hurt" to bats. In each mob, "minecraft:on_hurt" is set to run an event that includes the command, "say Ow!".
2. Activate this pack on a world and enable Holiday Creator experiments.
3. Make a 1 x 2 x 1 room for a blaze and a 1 x 1 x 1 room for a bat. Leave one block out of the side of the blaze room, and make one of the side blocks for the bat room a slab, so that you can hit each mob. Make one side wall block of each room a dispenser. Put arrows in the dispenser and a button on its side.
4. Spawn a blaze in the blaze room and a bat in the bat room.
5. Punch each mob, press the button on the dispenser to shoot each mob, and run the command </damage @e 1>.

Expected results

Each mob says "Ow!" when punched, when shot by a dispenser arrow, and when damaged by the damage command.

Observed results

The mobs do not say "Ow!"