*
 * <p>For instance, if <i>steps</i> is 5, one example sequence that will be tested is:
 *
 * <ol>
 *   <li>remove();
 *   <li>hasNext()
 *   <li>hasNext();
 *   <li>remove();
 *   <li>next();
 * </ol>
 *
 * <p>This particular order of operations may be unrealistic, and testing all 3^5 of them may be

     * <ul>
     *   <li>If it starts with either "pom." or "project.", the expression is evaluated against the model.</li>
     *   <li>If the value is null, get the value from the context.</li>
     *   <li>If the value is null, but the context contains the expression, don't replace the expression string
     *       with the value, and continue to find other expressions.</li>

 *
 * <p>Cache statistics are incremented according to the following rules:
 *
 * <ul>
 *   <li>When a cache lookup encounters an existing cache entry {@code hitCount} is incremented.
 *   <li>When a cache lookup first encounters a missing cache entry, a new entry is loaded.
 *       <ul>
 *         <li>After successfully loading an entry {@code missCount} and {@code loadSuccessCount}

  }

  /**
   * Verifies that a collection is immutable.
   *
   * <p>A collection is considered immutable if:
   *
   * <ol>
   *   <li>All its mutation methods result in UnsupportedOperationException, and do not change the
   *       underlying contents.
   *   <li>All methods that return objects that can indirectly mutate the collection throw
   *       UnsupportedOperationException when those mutators are called.
   * </ol>

 *
 * <p>Cache statistics are incremented according to the following rules:
 *
 * <ul>
 *   <li>When a cache lookup encounters an existing cache entry {@code hitCount} is incremented.
 *   <li>When a cache lookup first encounters a missing cache entry, a new entry is loaded.
 *       <ul>
 *         <li>After successfully loading an entry {@code missCount} and {@code loadSuccessCount}

 * </ol>
 *
 * <p>If your answers are:
 *
 * <ul>
 *   <li>(1) "no" and (2) "no", use {@link #forGraph(SuccessorsFunction)}.
 *   <li>(1) "yes" and (2) "yes", use {@link #forTree(SuccessorsFunction)}.
 *   <li>(1) "yes" and (2) "no", you can use either, but {@code forTree()} will be more efficient.
 *   <li>(1) "no" and (2) "yes", <b><i>neither will work</i></b>, but if you transform your node

     * <ul>
     * <li>collect all the vertices for the projects that we want to build.</li>
     * <li>iterate through the deps of each project and if that dep is within
     * the set of projects we want to build then add an edge, otherwise throw
     * the edge away because that dependency is not within the set of projects
     * we are trying to build. we assume a closed set.</li>
     * <li>do a topo sort on the graph that remains.</li>

     * Some spec examples are:
     * <ul>
     * <li><code>1.0</code> Version 1.0 as a recommended version</li>
     * <li><code>[1.0]</code> Version 1.0 explicitly only</li>
     * <li><code>[1.0,2.0)</code> Versions 1.0 (included) to 2.0 (not included)</li>
     * <li><code>[1.0,2.0]</code> Versions 1.0 to 2.0 (both included)</li>
     * <li><code>[1.5,)</code> Versions 1.5 and higher</li>

   * does not include "was cancelled." To be explicit: If this method returns a non-null value,
   * then:
   *
   * <ul>
   *   <li>{@code isDone()} must return {@code true}
   *   <li>{@code isCancelled()} must return {@code false}
   *   <li>{@code get()} must not block, and it must throw an {@code ExecutionException} with the
   *       return value of this method as its cause
   * </ul>
   */
  public static

 * <p>This tests:
 *
 * <ul>
 *   <li>comparing each object against itself returns true
 *   <li>comparing each object against null returns false
 *   <li>comparing each object against an instance of an incompatible class returns false
 *   <li>comparing each pair of objects within the same equality group returns true
 *   <li>comparing each pair of objects from different equality groups returns false
 *   <li>the hash codes of any two equal objects are equal