InputStream[] array = new InputStream[list.size()];
for (int i = 0; i < list.size(); i++) {
PDDocument d = list.get(i);
ByteArrayOutputStream bos = new ByteArrayOutputStream();
COSWriter writer = new COSWriter(bos);
writer.write(d);
array[i] = new ByteArrayInputStream(bos.toByteArray());
d.close();
}
document.close();