title: Findbugs 2.0 ThreadPoolExecutor.submit for void callable ignores exceptional return value
body: <p>I am using <code>java.util.concurrent.ExecutorService.submit(Callable&lt;T&gt;)</code> to invoke <code>Callable</code> tasks that return void. The reason that we chose <code>Callable</code> over <code>Runnable</code> was to leverage the ability of <code>Callable</code> to throw a checked exception because we don't really have a result. After moving to Findbugs 2.0, calls to submit are being flagged as violations because we are ignoring exceptional return value. Just wanted to check if this is a fair violation - because there is isn't much I want to do anyway with checking the return value.</p>
  
  <p>Thanks in advance!</p>