@EventHandler
public void on(PlayerInteractEvent e) {
    if (e.getHand() != EquipmentSlot.HAND) return;

    Block block = e.getClickedBlock();
    block.setType(Material.PLAYER_HEAD);
    block.getState().setType(Material.PLAYER_HEAD);
    //optional. The NPE can be forced this way
    //But it also shows without this line
    //((Skull) block.getState()).setOwnerProfile(null);
    block.getState().update(true);
}