* until a nonzero result is found; imposes "dictionary order." If the end of one iterable is
   * reached, but not the other, the shorter iterable is considered to be less than the longer one.
   * For example, a lexicographical natural ordering over integers considers {@code [] < [1] < [1,
   * 1] < [1, 2] < [2]}.
   *

 *
 * @author Jared Levy
 * @author Louis Wasserman
 * @since 2.0 (implements {@code NavigableSet} since 12.0)
 */
// TODO(benyu): benchmark and optimize all creation paths, which are a mess now
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // we're overriding default serialization
@ElementTypesAreNonnullByDefault
public abstract class ImmutableSortedSet<E> extends ImmutableSet<E>