code: private void assertSubRange(long from, long to) {
          if (!checkSubRange(from) || !checkSubRange(to)) {
              throw new IndexOutOfBoundsException("Required data for the sub list [" + from + "," + (to + 1) + "[ have "
                      + "not been loaded in the virtual list.");
          }
      }
docs: Asserts that the requested sub list is available in the virtual list. Otherwise it throws
  an IndexOutOfBoundsException.
  
  @param from the from index (inclusive)
  @param to   the to index (inclusive)