default Long clientSessionReauthenticationTimeNanos() {
        return null;
    }
Return the time on or after which a client should re-authenticate this
session, if any, otherwise null. The value is in nanoseconds as per
{@code System.nanoTime()} and is therefore only useful when compared to such
a value -- it's absolute value is meaningless. This value may be non-null
only on the client-side. It will be a random time between 85% and 95% of the
full session lifetime to account for latency between client and server and to
avoid re-authentication storms that could be caused by many sessions
re-authenticating simultaneously.

@return the time on or after which a client should re-authenticate this
        session, if any, otherwise null
clients/src/main/java/org/apache/kafka/common/network/Authenticator.java