CuboidRegion region = new CuboidRegion(world, min, max);
BlockArrayClipboard clipboard = new BlockArrayClipboard(region);

EditSession editSession = WorldEdit.getInstance().getEditSessionFactory().getEditSession(region.getWorld(), -1);

ForwardExtentCopy forwardExtentCopy = new ForwardExtentCopy(editSession, region, clipboard, region.getMinimumPoint());
forwardExtentCopy.setCopyingEntities(true);
Operations.complete(forwardExtentCopy);