Farm Warwick Greenskins (Bug) (Fallout 4)

In General sent me to the settlers of this farm to kill the super mutants at the plant Wilson Otomatis but the trouble is that I cleared out this location before taking the quest, killed all the super mutants including the name (big Mac). And now when I return the quest in this location - there are already all dead and the quest is not counted. Maybe someone knows the ID of this quest? on the Wiki only the quest Residents no ID of this quest. Waited for several days, but they don't respawn, roll back to an earlier save is not an option, I have more than 10 levels rose with the early saves.

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