customSet property
When codeLetterSet is OtpCodeLetterSet.custom, this string is the
allowed character set: only characters present in customSet can be
typed (plus digits 0-9 when codeType is
OtpCodeType.numbersAndLetters). Required to be non-empty in that
mode; ignored otherwise. Defaults to ''.
When codeLetterCasing is OtpCodeLetterCasing.uppercase or
OtpCodeLetterCasing.lowercase, matching is case-insensitive — so
customSet: 'abc' with OtpCodeLetterCasing.uppercase still accepts
A, B, C (and they end up displayed in uppercase). When the
casing is OtpCodeLetterCasing.mixed or null, matching is
case-sensitive, so customSet: 'abc' rejects A/B/C.
Implementation
final String customSet;