import valorless.havenbags.api.BagCreationObject ;
import valorless.havenbags.datamodels.Data ; // Bag Data

public void createBag ( ) {
    int size = 18 ;
    BagCreationObject creationObject = new BagCreationObject (size ) ;
    creationObject. setOwner (
        Bukkit. getPlayer ( "Valorless" ). getUniqueId ( ). toString ( )
    ) ; // UUID as String

    Data bagData = HavenBagsAPI. createBag (creationObject ) ; // Create & save new bag.
    bagData. setAutoPickup ( "mining" ) ;
    bagData. setAutoSort ( true ) ; // Any setters will automatically mark the data for saving.
}

private Data getBagData (ItemStack item ) {
    if (HavenBagsAPI. isBag (item ) ) { // Make sure the item is a bag.
        String bagUUID = HavenBagsAPI. getBagUUID (item ) ; // Get the bag's UUID.
        return HavenBagsAPI. getBag (bagUUID ) ; // Fetch the bag's Data.
    }
    else return null ; // Return null if the item is not a bag.
}