<p>Most <code>ExecutorService</code> objects must be explicitly shutdown,
otherwise, their internal threads can prolong the running of the JVM, even when everything
else has stopped.</p>

<p>FindBugs has detected that there are no calls to either the <code>shutdown()</code> or <code>shutdownNow()</code>
method, and thus, the <code>ExecutorService</code> is not guaranteed to ever terminate.  This is especially
problematic for <code>Executors.newFixedThreadPool()</code> and most of the other convenience methods in
the <code>Executors</code> class.</p>

<p>Even though there are some exceptions to this, particularly when a custom <code>ThreadFactory</code> is
provided, or for <code>ThreadPoolExecutor</code>s with <code>allowsCoreThreadTimeOut()</code> set to true,
it is good practice to explictly shutdown the <code>ExecutorService</code> when its utility is done.</p>