import java.util.logging.Logger;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * The concurrent hash map implementation built by {@link CacheBuilder}.
 *
 * <p>This implementation is heavily derived from revision 1.96 of <a
 * href="http://tinyurl.com/ConcurrentHashMap">ConcurrentHashMap.java</a>.
 *
 * @author Charles Fry

      return null;
    }
  }

  /** An admittedly inefficient implementation of {@link Map#containsKey}. */
  static boolean containsKeyImpl(Map<?, ?> map, @CheckForNull Object key) {
    return Iterators.contains(keyIterator(map.entrySet().iterator()), key);
  }

  /** An implementation of {@link Map#containsValue}. */
  static boolean containsValueImpl(Map<?, ?> map, @CheckForNull Object value) {

      return null;
    }
  }

  /** An admittedly inefficient implementation of {@link Map#containsKey}. */
  static boolean containsKeyImpl(Map<?, ?> map, @CheckForNull Object key) {
    return Iterators.contains(keyIterator(map.entrySet().iterator()), key);
  }

  /** An implementation of {@link Map#containsValue}. */
  static boolean containsValueImpl(Map<?, ?> map, @CheckForNull Object value) {