for (Map.Entry<Long,FastByIDMap<RunningAverage>> entry : averageDiffs.entrySet()) {
boolean matchesItemID1 = itemID == entry.getKey();
for (Map.Entry<Long,RunningAverage> entry2 : entry.getValue().entrySet()) {
RunningAverage average = entry2.getValue();
if (matchesItemID1) {
average.changeDatum(-prefDelta);
} else if (itemID == entry2.getKey()) {
average.changeDatum(prefDelta);
}
}
}