void normalize() {
            for (int i = size() - 1; i >= 0; i--) {
                Item lastItem = get(i);

                if (lastItem.isNull()) {
                    // remove null trailing items: 0, "", empty list
                    remove(i);
                } else if (!(lastItem instanceof ListItem)) {
                    break;
                }
            }
        }
Represents a version list item. This class is used both for the global item list and for sub-lists (which start
with '-(number)' in the version specification).
plugin/src/main/java/com/mcxiaoke/packer/ng/StringVersion.java