code: public static <K, E, V extends List<E>> List<E> getOrEmptyList(final Map<K, V> map, final Object key) {
          if (N.isNullOrEmpty(map)) {
              return N.<E> emptyList();
          }
  
          final V val = map.get(key);
  
          if (val != null || map.containsKey(key)) {
              return val;
          } else {
              return N.emptyList();
          }
      }
docs: Returns the value to which the specified key is mapped, or
  an empty immutable {@code List} if this map contains no mapping for the key.
  
  @param map
  @param key
  @return