Cannot deserialize field of type java.util.List

[LcyDev]

[15:37:30] [Server thread/INFO]: [BetterShulkerBoxes] Enabling BetterShulkerBoxes v4.1.0
[15:37:30] [Server thread/INFO]: Warning: Could not deserialize field of type java.util.List correctly!
[15:37:30] [Server thread/INFO]: SAVE CONFIG CALL
[15:37:30] [Server thread/INFO]: [BSB] BetterShulkerBoxes successfully hooked to WorldGuard

[lMartin3]

Mind sharing more info? Server version, plugin version, etc.