* terms</a>):
 *
 * <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 unique objects
 * </ul>
 *
 * <h3>Building a {@code Network}</h3>
 *

     * defined precedence onto each other to achieve proper precedence. Precedence is defined as:
     * <ul>
     *     <li>System properties (lowest precedence)</li>
     *     <li>Project properties (optional)</li>
     *     <li>User properties (highest precedence)</li>
     * </ul>
     * Note: Project properties contains properties injected from profiles, if applicable. Their precedence is

 *
 * <p>Some uses of this class include
 *
 * <ul>
 *   <li>As a method return type, as an alternative to returning {@code null} to indicate that no
 *       value was available
 *   <li>To distinguish between "unknown" (for example, not present in a map) and "known to have no
 *       value" (present in the map, with value {@code Optional.absent()})

   * The hashtable object. This can be either:
   *
   * <ul>
   *   <li>a byte[], short[], or int[], with size a power of two, created by
   *       CompactHashing.createTable, whose values are either
   *       <ul>
   *         <li>UNSET, meaning "null pointer"
   *         <li>one plus an index into the entries and elements array
   *       </ul>

/**
 * Provide a summary of the exception, containing:<ul>
 * <li>the exception itself,</li>
 * <li>useful end-user message,</li>
 * <li>useful reference to a solution, or set of solutions: this is usually a wiki page url in
 * <a href="http://cwiki.apache.org/confluence/display/MAVEN/">http://cwiki.apache.org/confluence/display/MAVEN/</a>,
 * </li>
 * <li>child exception summaries.</li>
 * </ul>
 */
public class ExceptionSummary {

 * 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
 * </ul>
 *
 * <p>{@code Graph} explicitly does not support parallel edges, and forbids implementations or

 * and performant but introduces some testing difficulties. This test exercises the two fallback
 * strategies.
 *
 * <ul>
 *   <li>SafeAtomicHelper: uses Atomic FieldsUpdaters to implement synchronization
 *   <li>SynchronizedHelper: uses {@code synchronized} blocks for synchronization
 * </ul>
 *
 * To force selection of our fallback strategies we load {@link AggregateFutureState} (and all of

/**
 * A helper which does some thread-safe operations for aggregate futures, which must be implemented
 * differently in GWT. Namely:
 *
 * <ul>
 *   <li>Lazily initializes a set of seen exceptions
 *   <li>Decrements a counter atomically
 * </ul>
 */
@GwtCompatible(emulated = true)
@ReflectionSupport(value = ReflectionSupport.Level.FULL)
@ElementTypesAreNonnullByDefault

 *       defined this way, but enough to live with.
 *   <li>If you override {@link #setUp} or {@link #tearDown}, make sure to invoke {@code
 *       super.setUp} and {@code super.tearDown} within them. These methods are used to clear and
 *       check for thread assertion failures.
 *   <li>All delays and timeouts must use one of the constants {@code SHORT_DELAY_MS}, {@code

   * following constraints. This is the callers responsibility and is not enforced here.
   *
   * <ul>
   *   <li>Both {@code xStats} and {@code yStats} must have the same {@code count}.
   *   <li>If that {@code count} is 1, {@code sumOfProductsOfDeltas} must be exactly 0.0.
   *   <li>If that {@code count} is more than 1, {@code sumOfProductsOfDeltas} must be finite.
   * </ul>
   */