in owners-common/src/main/java/com/googlesource/gerrit/owners/common/OwnersMap.java [82:94]
public void addFileOwners(String file, Set<Id> owners) {
if (owners.isEmpty()) {
return;
}
Set<Id> set = fileOwners.get(file);
if (set != null) {
// add new owners removing duplicates
set.addAll(owners);
} else {
fileOwners.put(file, Sets.newHashSet(owners));
}
}