How to use

getFilterItem

method

in

cofh.core.util.filter.ItemFilterWrapper

@Override
public void detectAndSendChanges() {
  ItemStack item = player.inventory.mainInventory.get(containerIndex);
  if (item.isEmpty() || item.getItem() != filterWrapper.getFilterItem()) {
    valid = false;
    return;
  }
  super.detectAndSendChanges();
}

public void onSlotChanged() {
  ItemStack item = player.inventory.mainInventory.get(containerIndex);
  if (valid && !item.isEmpty() && item.getItem() == filterWrapper.getFilterItem()) {
    player.inventory.mainInventory.set(containerIndex, filterWrapper.getFilterStack());
  }
}