code: public static long[] getContentRange(Map<String, String> headers) {
  		String value = getHeaderValue(headers, HTTP_CONTENT_RANGE_HEADER_UP);
  		if (value == null) return null;
  		return parseContentRange(value.trim());
  	}
docs: Return {@code Content-Range} response header field value.
  @param headers response header fields.
  @return Three element array with <em>first-byte-pos</em>, <em>last-byte-pos + 1</em>
  and <em>instance-length</em>, or {@code null} if {@code value} is syntactically invalid.