code: public Optional<V> findOne(final K key, final long maxTime, final TimeUnit timeUnit) {
          return ofNullable(collection()
                  .find(byId(key))
                  .maxTime(maxTime, timeUnit)
                  .map(this::decode)
                  .first());
      }
docs: Find a single value with the specified key, if existing.
  
  @param key      the key to search for
  @param maxTime  the maximum time for this request
  @param timeUnit the time unit in which {@code maxTime} is specified
  @return an Optional containing the requested value, or {@code Optional.empty()} if no value with this key exists