@NonNull
    public List<Trackable> getInventory() {
        return inventory == null ? Collections.emptyList() : Collections.unmodifiableList(inventory);
    }
Get the current inventory

@return the inventory of Trackables as unmodifiable collection. Use {@link #setInventory(List)} or
{@link #addInventoryItem(Trackable)} for modifications.
main/src/main/java/cgeo/geocaching/models/Geocache.java