return optional.orElse(null);
  }

  /**
   * Returns the minimum of the two values. If the values compare as 0, the first is returned.
   *
   * <p>The recommended solution for finding the {@code minimum} of some values depends on the type
   * of your data and the number of elements you have. Read more in the Guava User Guide article on

   * probability.
   *
   * <p>The constructed {@code BloomFilter} will be serializable if the provided {@code Funnel<T>}
   * is.
   *
   * <p>It is recommended that the funnel be implemented as a Java enum. This has the benefit of
   * ensuring proper serialization and deserialization, which is important since {@link #equals}
   * also relies on object identity of funnels.
   *

    return smear((o == null) ? 0 : o.hashCode());
  }

  private static final int MAX_TABLE_SIZE = Ints.MAX_POWER_OF_TWO;

  static int closedTableSize(int expectedEntries, double loadFactor) {
    // Get the recommended table size.
    // Round down to the nearest power of 2.
    expectedEntries = max(expectedEntries, 2);
    int tableSize = Integer.highestOneBit(expectedEntries);

 * #setException(Throwable)} or {@link #setFuture(ListenableFuture)} call. It can also, like any
 * other {@code Future}, be {@linkplain #cancel cancelled}.
 *
 * <p>{@code SettableFuture} is the recommended {@code ListenableFuture} implementation when your
 * task cannot be implemented with {@link ListeningExecutorService}, the various {@link Futures}

 * Implementations for common types can be found in {@link Funnels}.
 *
 * <p>Note that serialization of {@linkplain BloomFilter bloom filters} requires the proper
 * serialization of funnels. When possible, it is recommended that funnels be implemented as a
 * single-element enum to maintain serialization guarantees. See Effective Java (2nd Edition), Item
 * 3: "Enforce the singleton property with a private constructor or an enum type". For example:
 *

 * #setException(Throwable)} or {@link #setFuture(ListenableFuture)} call. It can also, like any
 * other {@code Future}, be {@linkplain #cancel cancelled}.
 *
 * <p>{@code SettableFuture} is the recommended {@code ListenableFuture} implementation when your
 * task cannot be implemented with {@link ListeningExecutorService}, the various {@link Futures}

import com.google.common.collect.Maps;
import java.util.Map;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * This class provides a skeletal implementation of {@link ValueGraph}. It is recommended to extend
 * this class rather than implement {@link ValueGraph} directly.
 *
 * <p>The methods implemented in this class should not be overridden unless the subclass admits a
 * more efficient implementation.
 *

 *
 * <p>The {@link MapIteratorCache} assumes ownership of the backing map, and cannot guarantee
 * correctness in the face of external mutations to the backing map. As such, it is <b>strongly</b>
 * recommended that the caller does not persist a reference to the backing map (unless the backing
 * map is immutable).
 *
 * <p>This class is tailored toward use cases in common.graph. It is *NOT* a general purpose map.
 *

In the ideal scenario the cache can fulfill the request without any conditional call to the network.
This will skip the normal events such as DNS, connecting to the network, and downloading the response body.

As recommended by the HTTP RFC the max age of a document is defaulted to 10% of the 
document's age at the time it was served based on "Last-Modified". Default expiration dates aren't used for URIs 
containing a query.

 - CallStart

     * available.
     *
     * @throws InterruptedException if the current thread was interrupted before or during the call
     *     (optional but recommended).
     * @throws CancellationException {@inheritDoc}
     */
    @CanIgnoreReturnValue
    @Override
    public V get(long timeout, TimeUnit unit)