code: public V getFirst(Object key) {
          List<V> res = getAll(key);
          if (res.isEmpty()) {
              return null;
          } else {
              return res.iterator().next();
          }
      }
docs: Get the first value for the given key, or <code>null</code> if there are no entries.
  
  @param key
  @return the first value or null.