code: public static <K, V, M extends Map<K, V>> void ifExist(M map,
              Consumer<M> consumer) {
          getOptional(map).ifPresent(consumer);
      }
docs: If exist.
  
  @param <K>      the type parameter
  @param <V>      the type parameter
  @param <M>      the type parameter
  @param map      the map
  @param consumer the consumer