private <N> Collection<N> getMultiValuedAttribute(
final AttributeDescription attributeDescription,
final Function<ByteString, N, NeverThrowsException> function) {
// The returned collection is unmodifiable because we may need to
// return an empty collection if the attribute does not exist in the
// underlying entry. If a value is then added to the returned empty
// collection it would require that an attribute is created in the
// underlying entry in order to maintain consistency.
final Attribute attr = entry.getAttribute(attributeDescription);
if (attr != null) {
return Collections.unmodifiableCollection(
Collections2.transformedCollection(attr, function, Functions.objectToByteString()));
} else {
return Collections.emptySet();
}
}
