hierarchyNavigator.prepareLookups("Image", "Fileset", filesetIdsMissing); for (final long filesetIdMissing : filesetIdsMissing) { final Set<Long> imageIdsRequiredUnordered = hierarchyNavigator.doLookup("Image", "Fileset", filesetIdMissing); final SortedSet<Long> imageIdsRequired = new TreeSet<Long>(imageIdsRequiredUnordered); final Set<Long> includedImageIds = Sets.intersection(imageIdsRequired, imageIds);