code: public LongStreamEx sorted(Comparator<Long> comparator) {
          return new LongStreamEx(stream().boxed().sorted(comparator).mapToLong(Long::longValue), context);
      }
docs: Returns a stream consisting of the elements of this stream sorted
  according to the given comparator. Stream elements are boxed before
  passing to the comparator.
  
  <p>
  For ordered streams, the sort is stable. For unordered streams, no
  stability guarantees are made.
  
  <p>
  This is a <a href="package-summary.html#StreamOps">stateful intermediate
  operation</a>.
  
  @param comparator a
  <a href="package-summary.html#NonInterference">non-interfering
  </a>, <a href="package-summary.html#Statelessness">stateless</a>
  {@code Comparator} to be used to compare stream elements
  @return the new stream