* href="https://github.com/google/guava/wiki/GraphsExplained#definitions">definitions of
 * terms</a>):
 *
 * <ul>
 *   <li>directed graphs
 *   <li>undirected graphs
 *   <li>graphs that do/don't allow self-loops
 *   <li>graphs whose nodes/edges are insertion-ordered, sorted, or unordered
 *   <li>graphs whose edges have associated values
 * </ul>
 *

  }

  /**
   * 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>

     * <li>The parent uses aggregation and refers to the child via the modules section</li>
     * <li>The module path to the child is considered to
     * point at the POM rather than its base directory if the path ends with ".xml" (ignoring case)</li>
     * <li>The name of the child's base directory matches the artifact id of the child.</li>
     * </ul>

 * actions taken by the java garbage collection system:
 *
 * <ul>
 *   <li>invoking the {@code finalize} methods of unreachable objects
 *   <li>clearing weak references to unreachable referents
 *   <li>enqueuing weak references to unreachable referents in their reference queue
 * </ul>
 *

 *   <li>Convert multiple instances "forward" using {@code converter.convertAll(as)}.
 *   <li>Convert in the "backward" direction using {@code converter.reverse().convert(b)} or {@code
 *       converter.reverse().convertAll(bs)}.
 *   <li>Use {@code converter} or {@code converter.reverse()} anywhere a {@link
 *       java.util.function.Function} is accepted (for example {@link java.util.stream.Stream#map
 *       Stream.map}).

 * Benchmarks (as of December 2011) show that:
 *
 * <ul>
 *   <li>for an unnested {@code lock()} and {@code unlock()}, a cycle detecting lock takes 38ns as
 *       opposed to the 24ns taken by a plain lock.
 *   <li>for nested locking, the cost increases with the depth of the nesting:
 *       <ul>
 *         <li>2 levels: average of 64ns per lock()/unlock()
 *         <li>3 levels: average of 77ns per lock()/unlock()

     * <ul>
     * <li>{@code *} (since 2.0.5)= everything,</li>
     * <li>{@code external:*}  (since 2.0.9)= everything not on the localhost and not file based,</li>
     * <li>{@code external:http:*} (since 3.8.0)= any repository not on the localhost using HTTP,</li>
     * <li>{@code repo,repo1}  (since 2.0.9)= {@code repo} or {@code repo1},</li>

 *
 * <ul>
 *   <li><b>Shallow immutability.</b> Elements can never be added, removed or replaced in this
 *       collection. This is a stronger guarantee than that of {@link
 *       Collections#unmodifiableCollection}, whose contents change whenever the wrapped collection
 *       is modified.
 *   <li><b>Null-hostility.</b> This collection will never contain a null element.

 * </ul>
 *
 * <p>This class is similar to {@link MoreExecutors#newSequentialExecutor}. This class is different
 * in a few ways:
 *
 * <ul>
 *   <li>Each task may be associated with a different executor.
 *   <li>Tasks may be of type {@code AsyncCallable}.
 *   <li>Running tasks <i>cannot</i> be interrupted. (Note that {@code newSequentialExecutor} does

 * </p>
 * <ul>
 * <li>{@literal file}</li>
 * <li>{@literal jar}</li>
 * <li>{@literal wsjar} (WebShpere独自プロトコル、{@literal jar}の別名)</li>
 * <li>{@literal zip} (WebLogic独自プロトコル、通常のZipファイルは{@literal jar}プロトコルを使用してください)</li>
 * <li>{@literal code-source} (Oracle AS(OC4J)独自プロトコル)</li>
 * <li>{@literal vfsfile} (JBossAS5独自プロトコル、{@literal file}の別名)</li>
 * <li>{@literal vfszip} (JBossAS5独自プロトコル)</li>
 * </ul>
 *
 * @author koichik