|This is one of the setup missions for the FIB Heist, which is called Blitz Play. Prior to starting the setup missions, you should get a text from Steve Haines that says for all three of the protagonists to meet them at the usual spot. This places a "B" marker on the map, which initiates a cutscene with the same name as the heist.|
Once the cutscene ends and you leave the area, you'll be in a conference call with all three characters, which will put a bunch of mission markers on your map. The one in the Mirror Park area will lead you to a Trashmaster, which will be moving. Stop in front of it and steal it, which will give you a 2-star wanted level. Lose the cops (hiding somewhere the cops can't easily get to), then bring the truck back to the lot where you met with the FIB to finish the mission.