In NetHandlerPlayClient#handleEntityStatus :
net.minecraft.client.network.NetHandlerPlayClient#handleEntityStatus Case 2 → Entity#performHurtAnimation() .
if (packetIn.getOpCode() == 2) Entity entity = packetIn.getEntity(this.clientController.netClientHandler); if (entity != null && !entity.isEntityInvulnerable()) if (entity.hurtResistantTime <= 0) // Already triggered locally? entity.performHurtAnimation();
Analysis and Implementation of the Hit Delay Fix for Minecraft 1.8.9