Previous oven, a delightful slide in double oven + cook top unit from 1980, was connected directly via 3-wire that came through the floor behind the unit.

New oven will be installed in a base cabinet in the same location. While in the process of finishing my basement several years ago I was forward thinking enough that I replaced the 3 wire with 4 wire throught the same hole in the floor.

New oven installation instructions shows that a j-box needs to be installed in an adjacent cabinet. Question is - is the j-box mandatory? If I have enough slack in the cable can I not wire it direcly to the oven?