This mod reveals Hoxton and Holdout as contacts that were originally hidden on the Contract Broker and makes their contracts selectable.
"Hoxton: heist_crime_spree" can be selected as a contract but WILL crash your game if you actually start it. Safehouse/Safe House Raids are safe.
"Holdout" Contracts should be relatively safe to play, with the added bonus of being able to select any map you wish to play in the new holdout game mode (You will crash if you select a Holdout level from the addons pack, choose default maps only.).