Which question are you attempting to answer? Could you be more explicit? Overriding what Container?
I am extending the ContainerPlayer class and overriding some of the methods, if that's what you mean. And I'm replacing the regular player.inventoryContainer with my player container during the EntityJoinWorldEvent. But you could have seen that from the code I posted earlier, so maybe you meant something else?
Oops, didn't catch that. The problem is that you call super in your Containers constructor so it adds all the slots that vanilla adds. Which is impossible to prevent. So you have to options.
[*]Override the slots by manually setting them in the inventorySlots field using List#set(int, Slot)
[*]Or switch to extending Container and adding the abilities/functions of the Players default container.
Note that overriding the Gui and Container may lead to incompatibility if done wrong.