code: public MultivaluedMap<String, String> pagerToParams(Pager... pager) {
  		MultivaluedMap<String, String> map = new MultivaluedHashMap<>();
  		if (pager != null && pager.length > 0) {
  			Pager p = pager[0];
  			if (p != null) {
  				map.put("page", Collections.singletonList(Long.toString(p.getPage())));
  				map.put("desc", Collections.singletonList(Boolean.toString(p.isDesc())));
  				map.put("limit", Collections.singletonList(Integer.toString(p.getLimit())));
  				if (p.getLastKey() != null) {
  					map.put("lastKey", Collections.singletonList(p.getLastKey()));
  				}
  				if (p.getSortby() != null) {
  					map.put("sort", Collections.singletonList(p.getSortby()));
  				}
  			}
  		}
  		return map;
  	}
docs: Converts a {@link Pager} object to query parameters.
  @param pager a Pager
  @return list of query parameters