public CaffeineCache<K, V> doWithAsync(final AsyncCallback<K, V> configurer) {
    requireNonNull(configurer, "Configurer callback is required.");
    this.callback = configurer::apply;
    return this;
  }
public CaffeineCache<K, V> doWithAsync(final AsyncCallback<K, V> configurer) {
    requireNonNull(configurer, "Configurer callback is required.");
    this.callback = configurer::apply;
    return this;
  }
public CaffeineCache < K , V > doWithAsync ( final AsyncCallback < K , V > configurer ) { requireNonNull ( configurer , "Configurer callback is required." ) ; this . callback = configurer :: apply ; return this ; }
Configure a cache builder and creates a new {@link AsyncLoadingCache}.

@param configurer Configurer callback.
@return This instance.
Configure a cache builder and creates a new { @link AsyncLoadingCache } .