I want them to be immigrants from a South American Maoist breakaway republic that happens to know a lot about chocolate. (Like maybe the USSR's chocolate imports had to be routed through there for a while.) They're unionized, well paid, and free to roam about the town. If you say anything racist to them they'll turn you into a blueberry and roll you into traffic, singing and dancing all the while.

Edit: the 1971 Willie Wonka movie canonically exists in the universe of the new movie. It was bankrolled by Wonka Corp. in order to get in front of a PR problem of some sort. It has developed a cult following but can't be shown on TV anymore because the oompa loompas are portrayed by white men in orangeface.

Edit 2: the earliest mentions of this group in the international media referred to it strictly as OOMPA ("Organización de Obreros Maoístas en Puno y Arequipa"), a name which still has some currency among the locals, although obviously the indigenous name is preferred. After OOMPA re-merged with its short-lived offshoot LOOMPA ("Leninist" OOMPA), the rather clunky modern name (which the locals tend not to like) began to appear in State Department publications and thereafter in mass media.