@Override
 public void entryUpdated(EntryEvent<K, V> entry) {
   K k = entry.getKey();
   ChoosableSet<V> entries = cache.get(k);
   if (entries != null) {
     entries.add(entry.getValue());
   }
 }
 private void addEntry(K k, V v) {
   ChoosableSet<V> entries = cache.get(k);
   if (entries == null) {
     entries = new ChoosableSet<>(1);
     ChoosableSet<V> prev = cache.putIfAbsent(k, entries);
     if (prev != null) {
       entries = prev;
     }
   }
   entries.add(v);
 }
 @Override
 public void get(final K k, final Handler<AsyncResult<ChoosableIterable<V>>> resultHandler) {
   ChoosableSet<V> entries = cache.get(k);
   Future<ChoosableIterable<V>> result = Future.future();
   if (entries != null && entries.isInitialised()) {
     result.setResult(entries).setHandler(resultHandler);
   } else {
     vertx.executeBlocking(
         () -> map.get(k),
         (AsyncResult<Collection<V>> res2) -> {
           Future<ChoosableIterable<V>> sresult = Future.future();
           if (res2.succeeded()) {
             Collection<V> entries2 = res2.result();
             ChoosableSet<V> sids;
             if (entries2 != null) {
               sids = new ChoosableSet<>(entries2.size());
               for (V hid : entries2) {
                 sids.add(hid);
               }
             } else {
               sids = new ChoosableSet<>(0);
             }
             ChoosableSet<V> prev = cache.putIfAbsent(k, sids);
             if (prev != null) {
               // Merge them
               prev.merge(sids);
               sids = prev;
             }
             sids.setInitialised();
             sresult.setResult(sids);
           } else {
             sresult.setFailure(result.cause());
           }
           sresult.setHandler(resultHandler);
         });
   }
 }