Custom Trait

You can add custom item traits by extending ItemTrait class:

class MyTrait extends ItemTrait {
    @Override
    public TraitData createData(ConfigurationSection configData) {
        return new MyTraitData(this);
    }

    @Override
    public void modifyMeta(ManyItemsStack stack, ItemMeta meta, TraitData data, ConfigurationSection configData) {
    }
    
    @Override
    public TraitData loadDataFromPOC(PersistentDataContainer container) {
        return new MyTraitData(this);
    }
}

• createData() create new trait data, based on user's configuration data
• modifyMeta() is used to modify the item display, such as display name or lore
• loadDataFromPOC() is used to load trait data from persistent data container, which is stored directly on items

You also need to create your own trait data class to store your item trait data:

class MyTraitData extends TraitData {

    private MyTrait trait;

    public MyTraitData(MyTrait trait) {
        this.trait = trait;
    }
    
    @Override
    public ItemTrait getTrait() {
        return this.trait;
    }
    
    @Override
    public void saveToPOC(PersistentDataContainer container) {
    }
}

• getTrait() returns the trait
• saveToPOC() is used to store trait data from persistent data container on items