Your installation is considered "hard wired" and you do not need a junction box as long as you wire the dishwasher directly into the electric line.

The last kitchen remodel I did, the owner didn't know if they wanted a dishwasher yet because the kitchen was so small, but they wanted power available in case they changed their minds in the future. In this case, I terminated the circuit in a junction box under the sink cabinet which was next to the cabinet that would have been removed to install a dishwasher.

As long as a dishwasher is a permanent part of your kitchen, you don't need to install a junction box and hard wiring as in your current configuration is the best choice and meets code.

What is not acceptable is terminating a circuit in a hidden junction box, like behind the dishwasher, because all junction boxes are required to be accessible to look for evidence of arcing during an inspection. In the case of a direct or hard wired dishwasher, the junction box is actually installed beneath the dishwasher where the electrical connection is made and is considered to be a safe way to wire an appliance.