Options:
  EnableHopperDropperSupport : true

Options:
  EnableHopperDropperSupport : false

public void openBookshelForPlayer (Block bookshelfBlock, Player player ) {
    //Get the location of the bookshelf Block
   Location location = bookshelfBlock. getLocation ( ) ;
    //Check if the bookshelf is loaded through the API
    if (BookshelfAPI. isBookshelfLoaded (location ) ) {
        //Get the inventory of that bookshelf through the API
       Inventory inventory = BookshelfAPI. getBookshelfInventory (location ) ;
        //Open the bookshelf
       player. openInventory (inventory ) ;
    }
}

#Whether to allow bookshelves to work with droppers and hoppers
  EnableHopperDropperSupport : true