public Long timeRemaining(TimeUnit unit) {
        synchronized (monitor) {
            if (timeout == null) {
                return null;
            }
            return unit.convert(timeout - (container().currentTimeMillis() - creationTime), TimeUnit.MILLISECONDS);
        }
    }
<p>Returns the time that this Request is allowed to exist. If no timeout has been set, this method will return
<em>null</em>.</p>

@param unit The unit to return the time in.
@return The number of time units left until this Request times out, or <em>null</em>.
jdisc_core/src/main/java/com/yahoo/jdisc/Request.java