Since rev 4.0.0, plugin use the OnMaxStackable(Item item) hook and this cause problem with other plugin that need to reduce the maximum stack size in container. Also ChestStackMultiplier conflict with StacksizeController and produce an error message .
"Calling hook OnMaxStackable resulted in a conflict between the following plugins ... "

For exemple, if you want to use with StackFuelGenerator with a stack of 100 instead of 500. you can fill the generator to 500 by moving fuel multiple time to the generator.  Same thing with ExcavatorLock.