public long reauthenticationBeginNanos() {
        return reauthenticationBeginNanos;
    }
Return the time when re-authentication began. 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.

@return the time when re-authentication began
clients/src/main/java/org/apache/kafka/common/network/ReauthenticationContext.java