Greenskins

(Location Name): Greenskins is a Minutemen radiant quest in Fallout 4. This quest can be started randomly when speaking to Preston Garvey or listening to Radio Freedom. If a settlement hasn't been unlocked yet, this quest may be started by speaking to a settler at that location and it will unlock the settlement.

Failure to kill the targeted super mutant in a timely manner will result in the failure of the quest.

Bugs
Starting the quest from The Slog: Unable to complete this task because of the above mentioned scenario, I cleared the banks before being assigned (looting) and can’t finish it now The target for the Brewery quest is in the kitchen of the Gwinett Restaurant, he will be marked.
 * It will sometimes have the player go to Faneuil Hall and even if you kill all the mutants there the quest will remain incomplete.
 * If the player has previously visited Breakheart Banks, and killed the supermutants, the quest will not update past the "Kill the Super Mutants" entry. The quest marker will show and will update while killing the mutants, but the player cannot turn the quest in.
 * Roger Warwick will sometimes not trigger dialogue to clear out a random location, making the quest impossible to complete. Fix is to, after you do a hard save, skip the dialog by typing in the console "sqt" to find your active quests, it will be called MinRecruit and have two numbers after it (ex. MinRecruit01). Then type "setstage (quest name) 100".
 * Occasionally the quest will send the player to kill Greenskins in Gwinnett Brewery, however there will be no quest pointer and there are no Supermutants in the Brewery itself, although there are some in the nearby Gwinett Restaurant and in the surrounding streets. It is unknown whether one of these is the target of the quest, although if this is the case the situation would be unique.  This issue has also been reported with Faneuil Hall.