tds/src/main/java/thredds/util/StringValidateEncodeUtils.java
public static boolean validPercentHexOctetsString(String percentHexOctetsString) {
    if (percentHexOctetsString == null)
      return false;
    Matcher m = VALID_PERCENT_HEX_OCTETS_PATTERN.matcher(percentHexOctetsString);
    return m.matches();
  }
public static boolean validPercentHexOctetsString(String percentHexOctetsString) {
    if (percentHexOctetsString == null)
      return false;
    Matcher m = VALID_PERCENT_HEX_OCTETS_PATTERN.matcher(percentHexOctetsString);
    return m.matches();
  }
Check that the given string is a valid percentHexOctets string. The
string is considered valid if it only contains a sequence of "%" prefixed,
two character strings where each two character string is composed only of
US-ASCII digits and upper- or lower-case A-F.
<p>
For example: "%31%32" or "%7b%7d%7E"

@param percentHexOctetsString the string to check for validity
@return true if the string is valid, false otherwise.