How would i go about setting a variable on a specific entity and retrieve it later?

FE:

	@SubscribeEvent
	public void entitySpawned(EntityJoinWorldEvent event)
	{
		Entity entity = event.getEntity();
		entity.setVariable("variableName",value); //set the variable
	}

	@SubscribeEvent
	public void onHurt(LivingHurtEvent event)
	{
		Entity entity = event.getEntity();
		if (!entity.getVariable("variableName")) return; //check the variable
	} 

 

Use capabilities.