@Override
    public boolean isPersistent() {
        return null != cookieExpiryDate;
    }
Returns {@code false} if the cookie should be discarded at the end
of the "session"; {@code true} otherwise.

@return {@code false} if the cookie should be discarded at the end
        of the "session"; {@code true} otherwise
httpclient5/src/main/java/org/apache/hc/client5/http/impl/cookie/BasicClientCookie.java