code: public static long[][] getRange(Map<String, String> headers) {
  		String rangeValue = getHeaderValue(headers, HTTP_RANGE_HEADER_UP);
  		if (rangeValue == null) return null;
  		rangeValue = rangeValue.trim();
  		return parseRanges(rangeValue);
  	}
docs: Get {@code Range} header field, and return parsed ranges.
  @param headers header fields.
  @return array of long[2] or {@code null} if {@code Range} header
  field is not present, or invalid.