The TSC website lists chicks that ship from Hoovers hatchery.
But I'm told that actual TSC stores order from several different hatcheries, so they may have come from somewhere else.
Some other hatcheries do sell Mottled Javas
Example:
https://www.privetthatchery.com/product/892
The black and white chicken is definitely mottled, which is a color that only occurs in a few breeds.
If she did come from Hoovers, the choices are really limited.
Hoovers has Anconas, another mottled breed:
https://hoovershatchery.com/ancona.html
But Anconas should have white earlobes, lay white eggs, and have a more slender body shape than the chicken in the photo. I don't think she looks right, but if your friend starts getting white eggs that chicken might be an Ancona after all.
Maybe a Mottled English Orptingon?
https://hoovershatchery.com/englishorpingtonvarietypack.html
This variety pack says it could include Mottled. I would expect an English Orpington to be fluffier, and I wouldn't expect very many of them to end up in assortments sold to stores, but I suppose it is a possibility.
I'm not seeing any other mottled breeds on Hoovers website. So either one of those, or from another hatchery, or something they don't have listed on their website but did ship in an assortment.