AlphaCase enum Null safety
This enum is used in order to specify which case to use for the alpha (letter) characters.
Note that AlphaCase.MIXED_CASE will cause the
mustHaveAtLeastOneOfEach property to consider it as being
two different "has" values.
For example, when using AlphaCase.MIXED_CASE and all the other "has" values as true, you must set minimum length to 4 because:
hasDigits = +1 hasSymbols = +1 hasAlpha = (using only lowercase or only uppercase) then +1 else +2
So the total sum = 4 (minimum length)
Otherwise, if you do not use
mustHaveAtLeastOneOfEach, the minimum
length is 1.