code: @Override
      public boolean removeFirstOccurrence(DelayedEntry entry) {
          DelayedEntry removedEntry = deque.pollFirst();
          if (removedEntry == null) {
              return false;
          }
          decreaseCountIndex(entry);
          return true;
      }
docs: Removes the first element of this queue instead of searching for it,
  implementation of this method is strongly tied with {@link StoreWorker} implementation.
  
  @param entry element to be removed.
  @return <code>true</code> if removed successfully, <code>false</code> otherwise