assertEquals(13.34112, branchPart.collectFreeEnergy().doubleValue(), 0.00001);
// can not collect the free energy more than once
assertEquals(new BigDecimal(0), branchPart.collectFreeEnergy());
int nbFall = 0;
for (ObservableTestHelper observerHelper : observerHelpers) {
assertEquals(1, observerHelper.nbUpdated());
int updateParam = (Integer) observerHelper.getUpdateObjects().get(0);
if (LeafUpdateMask.isFieldSet(updateParam, LeafUpdateMask.FALL_MASK)) {
// the single falling leaf (the first one)
assertTrue(LeafUpdateMask.isFieldSet(updateParam, LeafUpdateMask.AGE_MASK));
assertTrue(LeafUpdateMask.isFieldSet(updateParam, LeafUpdateMask.EFFICIENCY_MASK));