import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A strategy for determining whether two instances are considered equivalent, and for computing
 * hash codes in a manner consistent with that equivalence. Two examples of equivalences are the
 * {@linkplain #identity() identity equivalence} and the {@linkplain #equals "equals" equivalence}.
 *
 * @author Bob Lee
 * @author Ben Yu

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A strategy for determining whether two instances are considered equivalent, and for computing
 * hash codes in a manner consistent with that equivalence. Two examples of equivalences are the
 * {@linkplain #identity() identity equivalence} and the {@linkplain #equals "equals" equivalence}.
 *

   *       collections intelligently fall back to a binary search tree if hash table collisions are
   *       detected. Rather than going to all the trouble of reimplementing this ourselves, we
   *       simply switch over to use the JDK implementation wholesale if probable hash flooding is
   *       detected, sacrificing the compactness guarantee in very rare cases in exchange for much
   *       more reliable worst-case behavior.

   * exercise null handling fail on those subcollections.
   */
  public abstract static class NullsBefore implements Comparator<@Nullable String>, Serializable {
    /*
     * We don't serialize this class in GWT, so we don't care about whether GWT will serialize this
     * field.
     */
    @GwtTransient private final String justAfterNull;

    protected NullsBefore(String justAfterNull) {
      if (justAfterNull == null) {

  /**
   * Determines whether an edge has already been used during traversal. In the directed case a cycle
   * is always detected before reusing an edge, so no special logic is required. In the undirected
   * case, we must take care not to "backtrack" over an edge (i.e. going from A to B and then going
   * from B to A).
   */
  private static boolean canTraverseWithoutReusingEdge(

 *       <b>This may change in the future.</b>
 * </ul>
 *
 * <h3>Other notes</h3>
 *
 * <ul>
 *   <li>All ranges are shallow-immutable.
 *   <li>Instances of this type are obtained using the static factory methods in this class.
 *   <li>Ranges are <i>convex</i>: whenever two values are contained, all values in between them
 *       must also be contained. More formally, for any {@code c1 <= c2 <= c3} of type {@code C},

   * all subscribers in the order they are posted.
   *
   * <p>When all subscribers are dispatched to using a <i>direct</i> executor (which dispatches on
   * the same thread that posts the event), this yields a breadth-first dispatch order on each
   * thread. That is, all subscribers to a single event A will be called before any subscribers to

   * }</pre>
   *
   * <p>By default, the order in which cells are added to the builder determines the iteration
   * ordering of all views in the returned table, with {@link #putAll} following the {@link
   * Table#cellSet()} iteration order. However, if {@link #orderRowsBy} or {@link #orderColumnsBy}
   * is called, the views are sorted by the supplied comparators.
   *

   * safe to do so. The exact circumstances under which a copy will or will not be performed are
   * undocumented and subject to change.
   *
   * <p>This method is not type-safe, as it may be called on elements that are not mutually
   * comparable.
   *
   * @throws ClassCastException if the elements are not mutually comparable
   * @throws NullPointerException if any of {@code elements} is null
   */

 * documented. Exceptions to this are {@link #containsKey}, {@link #size}, {@link #isEmpty}, {@link
 * #asMap}, and {@link #toString}.
 *
 * <p>Instances of this class may be used by multiple threads concurrently. All operations are
 * atomic unless otherwise noted.
 *
 * <p>Instances of this class are serializable if the keys are serializable.
 *