Can someone explain "Heal Reactivity" to me?

I read in the 18.7.0 update notes that there is a new stat called "Heal Reactivity". I don't see this stat as one that I can put IP into, so I presume that it's some internal stat that is computed based on other stats or is one that you simply can't put IP into, but can be buffed or debuffed. I don't see "Heal Reactivity" as one of the fields that can be searched on aoitems. Can someone explain to me what affects "Heal Reactivity" and what "Heal Reactivity" affects? For instance, does it improve the healing ability of HoT as well as regular heals? What about complete heals?

https://aoitems.com/nano/strain/1055/

It's in other nanos too, it increases the amount of healing you receive from a given source it's as yet unconfirmed what the +20 means, it may mean +20%; the opposite is true of other nano lines like.
https://aoitems.com/nano/strain/1056/
Where heal reactivity is reduced by a factor of -50 again this may be 50% less healing received but I've not check any confirmation.

Heal Reactivity is, as Caloss2 stated, on some nanos.
It's basically like Heal Efficiency except for you receiving healing instead of giving healing like HE is.