}
// Update existing group:
for (int compIDX = 0;; compIDX++) {
final FieldComparator fc = comparators[compIDX];
fc.copy(spareSlot, doc);
final int c = reversed[compIDX] * fc.compare(group.comparatorSlot, spareSlot);
if (c < 0) {
// Definitely not competitive.
return;