* expressions it can be specified even more easily:
 *
 * {@snippet :
 * CacheLoader<Key, Graph> loader = CacheLoader.from(key -> createExpensiveGraph(key));
 * }
 *
 * @author Charles Fry
 * @since 10.0
 */
@GwtCompatible
public abstract class CacheLoader<K, V> {
  /** Constructor for use by subclasses. */
  protected CacheLoader() {}

  /**
   * Computes or retrieves the value corresponding to {@code key}.
   *

 * more simply:
 *
 * {@snippet :
 * CacheLoader<Key, Graph> loader = CacheLoader.from(key -> createExpensiveGraph(key));
 * }
 *
 * @author Charles Fry
 * @since 10.0
 */
@GwtCompatible
public abstract class CacheLoader<K, V> {
  /** Constructor for use by subclasses. */
  protected CacheLoader() {}

  /**
   * Computes or retrieves the value corresponding to {@code key}.
   *

/**
 * Utility {@link CacheLoader} implementations intended for use in testing.
 *
 * @author mike nonemacher
 */
@GwtCompatible
@NullUnmarked
final class TestingCacheLoaders {

  /**
   * Returns a {@link CacheLoader} that implements a naive {@link CacheLoader#loadAll}, delegating
   * {@link CacheLoader#load} calls to {@code loader}.
   */
  static <K, V> CacheLoader<K, V> bulkLoader(CacheLoader<K, V> loader) {

   *
   * <p>Caches loaded by a {@link CacheLoader} will issue a single request to {@link
   * CacheLoader#loadAll} for all keys which are not already present in the cache. All entries
   * returned by {@link CacheLoader#loadAll} will be stored in the cache, over-writing any
   * previously cached values. This method will throw an exception if {@link CacheLoader#loadAll}

   *
   * <p>Caches loaded by a {@link CacheLoader} will issue a single request to {@link
   * CacheLoader#loadAll} for all keys which are not already present in the cache. All entries
   * returned by {@link CacheLoader#loadAll} will be stored in the cache, over-writing any
   * previously cached values. This method will throw an exception if {@link CacheLoader#loadAll}

/**
 * Utility {@link CacheLoader} implementations intended for use in testing.
 *
 * @author mike nonemacher
 */
@GwtCompatible
@NullUnmarked
final class TestingCacheLoaders {

  /**
   * Returns a {@link CacheLoader} that implements a naive {@link CacheLoader#loadAll}, delegating
   * {@link CacheLoader#load} calls to {@code loader}.
   */
  static <K, V> CacheLoader<K, V> bulkLoader(CacheLoader<K, V> loader) {

    AtomicInteger loadCount = new AtomicInteger();
    AtomicInteger reloadCount = new AtomicInteger();
    AtomicInteger loadAllCount = new AtomicInteger();

    CacheLoader<Object, Object> baseLoader =
        new CacheLoader<Object, Object>() {
          @Override
          public Object load(Object key) {
            loadCount.incrementAndGet();
            return new Object();
          }

 *
 * <p>The core interface used to represent caches is {@link Cache}. In-memory caches can be
 * configured and created using {@link CacheBuilder}, with cache entries being loaded by {@link
 * CacheLoader}. Statistics about cache performance are exposed using {@link CacheStats}.
 *
 * <p>See the Guava User Guide article on <a
 * href="https://github.com/google/guava/wiki/CachesExplained">caches</a>.
 *

   *   <li>consolidation of the loader logic to {@linkplain CacheBuilder#build(CacheLoader) a single
   *       authoritative location}
   *   <li>{@linkplain LoadingCache#refresh refreshing of entries}, including {@linkplain
   *       CacheBuilder#refreshAfterWrite automated refreshing}
   *   <li>{@linkplain LoadingCache#getAll bulk loading requests}, including {@linkplain
   *       CacheLoader#loadAll bulk loading implementations}
   * </ul>
   *

 * strengths.
 *
 * @author mike nonemacher
 */
@NullUnmarked
public class CacheReferencesTest extends TestCase {

  private static final CacheLoader<Key, String> KEY_TO_STRING_LOADER =
      new CacheLoader<Key, String>() {
        @Override
        public String load(Key key) {
          return key.toString();
        }
      };