### Question:
RedundancyCalculator { public static boolean canRestoreRedundancy(Layout layout, String server) { if (layout.getSegments().size() == 1) { return false; } else { IntPredicate nodeNotPresent = currentIndex -> Sets.difference( layout.getSegments().get(currentIndex).getAllLogServers(), layout.getSegments().get(currentIndex - 1).getAllLogServers() ).contains(server); return IntStream.range(1, layout.getSegments().size()) .boxed() .reduce(false, (nodePresentSoFar, currentIndex) -> nodePresentSoFar || nodeNotPresent.test(currentIndex), (nodePresentBefore, nodePresentNow) -> nodePresentBefore || nodePresentNow); } }  Layout updateLayoutAfterRedundancyRestoration(
            List<TransferSegment> segments, Layout initLayout); static boolean canRestoreRedundancy(Layout layout, String server); static boolean canMergeSegments(Layout layout); static boolean canRestoreRedundancyOrMergeSegments(Layout layout, String server); ImmutableList<TransferSegment> createStateList(Layout layout, long trimMark); ImmutableList<TransferSegment> getTrimmedNotRestoredSegments(Layout layout, long trimMark); ImmutableList<TransferSegmentRange> prepareTransferWorkload(
            ImmutableList<TransferSegment> transferSegmentList,
            Optional<Long> committedTail);  }### Answer:
@Test public void testRequiresRedundancyRestoration() { LayoutStripe stripe0 = new LayoutStripe(Collections.singletonList("A")); LayoutStripe stripe1 = new LayoutStripe(Arrays.asList("A", "B")); LayoutStripe stripe2 = new LayoutStripe(Arrays.asList("A", "B", "localhost")); LayoutSegment segment0 = new LayoutSegment(CHAIN_REPLICATION, 0L, 2L, Collections.singletonList(stripe0)); LayoutSegment segment1 = new LayoutSegment(CHAIN_REPLICATION, 3L, 6L, Collections.singletonList(stripe1)); LayoutSegment segment2 = new LayoutSegment(CHAIN_REPLICATION, 6L, 9L, Collections.singletonList(stripe2)); Layout layout = createTestLayout(Arrays.asList(segment1, segment2)); assertThat(RedundancyCalculator.canRestoreRedundancy(layout, "A")) .isFalse(); layout = createTestLayout(Collections.singletonList(segment1)); assertThat(RedundancyCalculator.canRestoreRedundancy(layout, "A")) .isFalse(); layout = createTestLayout(Arrays.asList(segment0, segment1, segment2)); assertThat(RedundancyCalculator.canRestoreRedundancy(layout, "B")) .isTrue(); layout = createTestLayout(Arrays.asList(segment0, segment2)); assertThat(RedundancyCalculator.canRestoreRedundancy(layout, "localhost")) .isTrue(); }