generateV4 method
Generates a random v4 UUID string.
The UUID format is 8-4-4-4-12 hex digits, with the version and variant bits set according to the spec.
Implementation
String generateV4() {
// Generate variant (y) bits: 8, 9, A, or B
final int special = 8 + _random.nextInt(4);
return '${_bitsDigits(16, 4)}${_bitsDigits(16, 4)}-' // 8 hex digits
'${_bitsDigits(16, 4)}-' // 4 hex digits
'4${_bitsDigits(12, 3)}-' // '4' + 3 hex digits (version 4)
'${_printDigits(special, 1)}${_bitsDigits(12, 3)}-' // variant + 3 hex digits
'${_bitsDigits(16, 4)}${_bitsDigits(16, 4)}${_bitsDigits(16, 4)}'; // 12 hex digits
}