This fixed player rubberbanding when touching the wall of a containment field for me.
I took the liberty of uncommenting some code which produces a sound when the player tries to leave the field, and also deleted line 113 along with everything related to it since it seemed unnecessary.
I've tested this on singleplayer and on my 200ms multiplayer server and appears to be working perfectly in both.
(It works even if allow-flight is set to false on server.properties; I also tried using an elytra, levitation effect and extra speed, which all worked well too).
All tests were done using Forge-2860
Rodro
45994e2b94