@Override
    public Date getExpiryDate() {
        return cookieExpiryDate;
    }
Returns the expiration {@link Date} of the cookie, or {@code null}
if none exists.
<p><strong>Note:</strong> the object returned by this method is
considered immutable. Changing it (e.g. using setTime()) could result
in undefined behaviour. Do so at your peril. </p>
@return Expiration {@link Date}, or {@code null}.

@see #setExpiryDate(Date)
ngrinder-runtime/src/main/java/org/apache/hc/client5/http/impl/cookie/BasicClientCookie.java