public final boolean containsSingle(
@Nullable final KEYTYPE aKey, @Nullable final VALUETYPE aValue) {
final COLLTYPE aCont = get(aKey);
return aCont != null && aCont.contains(aValue);
}
@Nonnull
public final EChange removeSingle(
@Nullable final KEYTYPE aKey, @Nullable final VALUETYPE aValue) {
final COLLTYPE aCont = get(aKey);
return aCont == null ? EChange.UNCHANGED : EChange.valueOf(aCont.remove(aValue));
}