Riptide does not work when inside a cauldron filled with water

Summary:
Riptide will not work when in a full cauldron with water even though the player is in water.

Steps to Reproduce:

1. Fill a cauldron with water
2. Enchant a trident with Riptide
3. Stand inside the cauldron
4. Use the trident

Observed Results:
Nothing happens.

Expected Results:
The player should be launched.