@Override
        public void failed(Throwable t) {
            completeExceptionally(t);
        }
<p>Closes the underlying {@link ContentChannel}. If {@link CompletionHandler#failed(Throwable)} is called,
either of the get() methods will rethrow that Throwable.</p>
jdisc_core/src/main/java/com/yahoo/jdisc/handler/FastContentWriter.java