Answer by ilhan for How to generate a random alpha-numeric string

You need org.apache.commons:commons-lang3:3.18.0https://mvnrepository.com/artifact/org.apache.commons/commons-lang3/3.18.0

String randomString = RandomStringUtils.insecure().nextAlphanumeric(12);

If you want upper case:

String upperCaseRandomString = randomString.toUpperCase();