/**
  * @param c Cache.
  * @param qry Query.
  * @param args Arguments.
  * @return Column as list.
  */
 private static <X> List<X> columnQuery(IgniteCache<?, ?> c, String qry, Object... args) {
   return column(0, c.query(new SqlFieldsQuery(qry).setArgs(args)).getAll());
 }