code: @SuppressWarnings("unchecked")
    public final IntCache<V> buildForIntKey() {
      Cache2kConfiguration<K,V> cfg = config();
      if (cfg.getKeyType().getType() != Integer.class) {
        throw new IllegalArgumentException("Integer key type expected, was: " + cfg.getKeyType());
      }
      return (IntCache<V>) CacheManager.PROVIDER.createCache(manager, config());
    }
docs: Builds a cache with the specified configuration parameters.
  The behavior is identical to {@link #build()} except that it checks that
  the key type is {@code Integer} and casts the created cache to the specialized
  interface.
  
  @throws IllegalArgumentException if a cache of the same name is already active in the cache manager
  @throws IllegalArgumentException if key type is unexpected
  @throws IllegalArgumentException if a configuration entry for the named cache is required but not present