}
    }
    return features;
  }

  /**
   * Given a set of features, return a new set of all features directly or indirectly implied by any
   * of them.
   *
   * @param features the set of features whose implications to find
   * @return the implied set of features
   */
  public static Set<Feature<?>> impliedFeatures(Set<Feature<?>> features) {
    Set<Feature<?>> impliedSet = new LinkedHashSet<>();

  @Deprecated
  public static <V extends @Nullable Object> FluentFuture<V> from(FluentFuture<V> future) {
    return checkNotNull(future);
  }

  /**
   * Returns a {@code Future} whose result is taken from this {@code Future} or, if this {@code
   * Future} fails with the given {@code exceptionType}, from the result provided by the {@code

 *
 * <ul>
 *   <li>directed graphs
 *   <li>undirected graphs
 *   <li>graphs that do/don't allow parallel edges
 *   <li>graphs that do/don't allow self-loops
 *   <li>graphs whose nodes/edges are insertion-ordered, sorted, or unordered
 *   <li>graphs whose edges are <a
 *       href="https://github.com/google/guava/wiki/GraphsExplained#uniqueness">unique</a> objects
 * </ul>
 *
 * <h3>Building a {@code Network}</h3>
 *

      }
    }
    return features;
  }

  /**
   * Given a set of features, return a new set of all features directly or indirectly implied by any
   * of them.
   *
   * @param features the set of features whose implications to find
   * @return the implied set of features
   */
  public static Set<Feature<?>> impliedFeatures(Set<Feature<?>> features) {
    Set<Feature<?>> impliedSet = new LinkedHashSet<>();

   *
   * This returns null if:
   *
   *  * The stream is exhausted.
   *  * We've read all of the bytes of an object whose length is known.
   *  * We've reached the [DerHeader.TAG_END_OF_CONTENTS] of an object whose length is unknown.
   */
  fun peekHeader(): DerHeader? {
    var result = peekedHeader

    if (result == null) {
      result = readHeader()

import java.util.Collection;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * An interface for <a
 * href="https://en.wikipedia.org/wiki/Graph_(discrete_mathematics)">graph</a>-structured data,
 * whose edges are anonymous entities with no identity or information of their own.
 *
 * <p>A graph is composed of a set of nodes and a set of edges connecting pairs of nodes.
 *

  @ParametricNullness
  protected abstract E get(int index);

  /**
   * Constructs an iterator across a sequence of the given size whose initial position is 0. That
   * is, the first call to {@link #next()} will return the first element (or throw {@link
   * NoSuchElementException} if {@code size} is zero).
   *

import java.time.Duration;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
import org.jspecify.annotations.NullMarked;

/**
 * A Ticker whose value can be advanced programmatically in test.
 *
 * <p>The ticker can be configured so that the time is incremented whenever {@link #read} is called:
 * see {@link #setAutoIncrementStep}.
 *
 * <p>This class is thread-safe.

   * Returns a new array that prepends {@code element} to {@code array}.
   *
   * @param element the element to prepend to the front of {@code array}
   * @param array the array of elements to append
   * @return an array whose size is one larger than {@code array}, with {@code element} occupying
   *     the first position, and the elements of {@code array} occupying the remaining elements.
   */

                : Optional.of(getVersions().get(getVersions().size() - 1));
    }

    /**
     * Gets the repository from which the specified version was resolved.
     *
     * @param version The version whose source repository should be retrieved, must not be {@code null}
     * @return An Optional containing the repository from which the version was resolved,
     *         or empty Optional if the repository is unknown
     */