pm.getObjectIdClass(Article.class);
// get the sequence
Sequence s = pm.getSequence(ARTICLE_SEQ);
assertNotNull("Sequence " + ARTICLE_SEQ + " should not be null.", s);
s.allocate(ADDITIONAL);
Article articles[] = new Article[ADDITIONAL];
for (int i = 0; i < ADDITIONAL; i++) {
if (i%2 == 0) {
articles[i] = new Service();
} else {
articles[i] = new Materiel();