public final boolean isShutdown() {
        return done.getCount() == 0;
    }
<p>This is a convenient parent class for {@link ClientApplication} developers. It extends {@link AbstractApplication}
and implements {@link Runnable} to wait for {@link #shutdown()} to be called. When using this class, you implement
{@link #start()} (and optionally {@link #stop()}), and provide a reference to it to whatever component is responsible
for signaling shutdown.</p>

@author Simon Thoresen Hult
jdisc_core/src/main/java/com/yahoo/jdisc/client/AbstractClientApplication.java