Apache Druid: Kerberos authenticaton chooses a cryptographically unsecure secret if not configured explicitly.

Apache Druid’s Kerberos authenticator uses a weak fallback secret when the `druid.auth.authenticator.kerberos.cookieSignatureSecret` configuration is not explicitly set. In this case, the secret is generated using `ThreadLocalRandom`,
which is not a crypto-graphically secure random number generator. This
may allow an attacker to predict or brute force the secret used to sign
authentication cookies, potentially enabling token forgery or
authentication bypass. Additionally, each process generates its own
fallback secret, resulting in inconsistent secrets across nodes. This
causes authentication failures in distributed or multi-broker
deployments, effectively leading to a incorrectly configured clusters. Users are
advised to configure a strong `druid.auth.authenticator.kerberos.cookieSignatureSecret`

This issue affects Apache Druid: through 34.0.0.

Users are recommended to upgrade to version 35.0.0, which fixes the issue making it mandatory to set `druid.auth.authenticator.kerberos.cookieSignatureSecret` when using the Kerberos authenticator. Services will fail to come up if the secret is not set.