[VALIDATOR-496] IBANValidator: Fix IBAN 'c' pattern according to specification

[slawekjaranowski]

No description provided.

[sebbASF]

I agree that the PDF file says that 'c' includes lower-case, however that may not be the full story.

Please see the comments here:

commons-validator/src/main/java/org/apache/commons/validator/routines/IBANValidator.java

Lines 234 to 258 in f9073b1

	* Wikipedia [1] says that only uppercase is allowed.
	* The SWIFT PDF file [2] implies that lower case is allowed.
	* However there are no examples using lower-case.
	* Unfortunately the relevant ISO documents (ISO 13616-1) are not available for free.
	* The IBANCheckDigit code treats upper and lower case the same,
	* so any case validation has to be done in this class.
	*
	* Note: the European Payments council has a document [3] which includes a description
	* of the IBAN. Section 5 clearly states that only upper case is allowed.
	* Also the maximum length is 34 characters (including the country code),
	* and the length is fixed for each country.
	*
	* It looks like lower-case is permitted in BBANs, but they must be converted to
	* upper case for IBANs.
	*
	* [1] https://en.wikipedia.org/wiki/International_Bank_Account_Number
	* [2] http://www.swift.com/dsp/resources/documents/IBAN_Registry.pdf (404)
	* => https://www.swift.com/sites/default/files/resources/iban_registry.pdf
	* The above is an old version (62, Jan 2016)
	* As of May 2020, the current IBAN standards are located at:
	* https://www.swift.com/standards/data-standards/iban
	* The above page contains links for the PDF and TXT (CSV) versions of the registry
	* Warning: these may not agree -- in the past there have been discrepancies.
	* The TXT file can be used to determine changes which can be cross-checked in the PDF file.
	* [3] http://www.europeanpaymentscouncil.eu/documents/ECBS%20IBAN%20standard%20EBS204_V3.2.pdf

[sebbASF]

The following documents also say that IBAN is upper-case only:

http://www.pruefziffernberechnung.de/Originaldokumente/IBAN/SIG203V3FV_181200.pdf (section 5.1, p9)
https://www.ecbs.org/Download/EBS204_V3.2.pdf (sect 5.1)

[slawekjaranowski]

@sebbASF thanks ... so I close it 😄