The new /damage command lets you specify the type of damage. One such option is lightning. One would expect that you can use this option to charge creepers, convert mooshrooms, and so on.

That does not work. The only special lightning interaction that works is lightning instantly killing turtles.

How to reproduce

/summon turtle
/damage @e[type=turtle] 1 lightning

It dies because lightning does extra damage to turtles

/summon creeper
/damage @e[type=creeper] 1 lightning

It doesn't charge even though it took lightning damage

Cause
The reason for this is pretty obvious, turtles check for "cause":"lightning" in their damage sensor, but creepers and other things check for the lightning family in the damaging entity. Making this consistent is trivially easy and will fix this problem.