* {@link Collections#singleton(Object)} and <a
 * href="https://docs.oracle.com/javase/9/docs/api/java/util/Set.html#immutable">{@code Set.of}</a>,
 * we recommend using <i>these</i> classes instead for this reason (as well as for consistency).
 *
 * <h4>Creation</h4>
 *
 * <p>Except for logically "abstract" types like {@code ImmutableCollection} itself, each {@code

 * {@link Collections#singleton(Object)} and <a
 * href="https://docs.oracle.com/javase/9/docs/api/java/util/Set.html#immutable">{@code Set.of}</a>,
 * we recommend using <i>these</i> classes instead for this reason (as well as for consistency).
 *
 * <h4>Creation</h4>
 *
 * <p>Except for logically "abstract" types like {@code ImmutableCollection} itself, each {@code

 *       noted in the method descriptions below.
 *   <li>Streams include primitive-specialized variants such as {@code IntStream}, the use of which
 *       is strongly recommended.
 *   <li>Streams are standard Java, not requiring a third-party dependency (but do render your code
 *       incompatible with Java 7 and earlier).
 * </ul>
 *
 * <h3>Example</h3>
 *