code: public static void serializeEntry(final Entry entry, final Writer writer) throws IllegalArgumentException, FeedException, IOException {
  
          // Build a feed containing only the entry
          final List<Entry> entries = new ArrayList<Entry>();
          entries.add(entry);
          final Feed feed1 = new Feed();
          feed1.setFeedType("atom_1.0");
          feed1.setEntries(entries);
  
          // Get Rome to output feed as a JDOM document
          final WireFeedOutput wireFeedOutput = new WireFeedOutput();
          final Document feedDoc = wireFeedOutput.outputJDom(feed1);
  
          // Grab entry element from feed and get JDOM to serialize it
          final Element entryElement = feedDoc.getRootElement().getChildren().get(0);
  
          final XMLOutputter outputter = new XMLOutputter();
          outputter.output(entryElement, writer);
      }
docs: Utility method to serialize an entry to writer.