* are broken arbitrarily.
   *
   * <p>For example:
   *
   * <pre>{@code
   * Stream.of("foo", "quux", "banana", "elephant")
   *     .collect(greatest(2, comparingInt(String::length)))
   * // returns {"elephant", "banana"}
   * }</pre>
   *
   * <p>This {@code Collector} uses O(k) memory and takes expected time O(n) (worst-case O(n log