Reject vowels in SedolCheckDigit

[sahvx655-wq]

SedolCheckDigit.toInt already rejects out-of-range and non-alphanumeric characters, but it accepts vowels. The SEDOL alphabet deliberately omits A, E, I, O and U (as noted in the Wikipedia reference in the class Javadoc), so no genuine SEDOL contains one. Whilst working through these routines I generated a correct modulus-10 check digit for bodies containing vowels and found SEDOL_CHECK_DIGIT.isValid returning true for codes such as B0AKT02 and AAAAAA0. There is no SedolValidator wrapping this routine, so SedolCheckDigit.isValid is the only public SEDOL entry point and the over-acceptance is user visible: a string that can never be a real SEDOL passes validation purely because its check digit happens to line up.

The fix rejects vowels in toInt, next to the existing alphanumeric-range check, which is where the other per-character SEDOL rules already live, so the whole character set stays enforced in one place rather than being pushed onto callers. The added test asserts vowel-bearing codes with valid check digits are rejected while the existing consonant fixtures still validate; it fails before the change and passes after.

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[garydgregory]

Hello @sahvx655-wq

Thank you for the PR.

• Use a parameterized test instead of a loop
• Add test fixtures that check each vowel indidivually.

TY!