MalformedByteSequenceException parsing RSS feed with ROME

Im getting a MalformedByteSequenceException running a JSF application which makes use of the Rome Rss-parsing Lib:

[2017-08-31T15:54:01.241+0200] [glassfish 5.0] [SEVERE] [] [] [tid: _ThreadID=101 _ThreadName=Thread-9] [timeMillis: 1504187641241] [levelValue: 1000] [[  com.sun.org.apache.xerces.internal.impl.io.MalformedByteSequenceException: Ungültiges Byte 1 von 1-Byte-UTF-8-Sequenz.    at com.sun.org.apache.xerces.internal.impl.io.UTF8Reader.invalidByte(UTF8Reader.java:701)    at com.sun.org.apache.xerces.internal.impl.io.UTF8Reader.read(UTF8Reader.java:567)    at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.load(XMLEntityScanner.java:1793)    at com.sun.org.apache.xerces.internal.impl.XMLEntityScanner.skipChar(XMLEntityScanner.java:1463)    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2824)    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:606)    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:848)    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:777)    at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)    at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:243)    at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:339)    at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:121)    at main.java.tools.RssAggregator.searchAggregatedFeeds(RssAggregator.java:119)    at main.java.jobs.ApplicationRunnable.lambda$execute$0(ApplicationRunnable.java:45)    at java.lang.Iterable.forEach(Iterable.java:75)    at main.java.jobs.ApplicationRunnable.execute(ApplicationRunnable.java:43)    at org.quartz.core.JobRunShell.run(JobRunShell.java:213)    at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:557)]]

The error is thrown in RssAggregator.searchAggregatedFeeds() line 119:

public List<Feed> searchAggregatedFeeds(String keyword) {    keyword = keyword.toLowerCase();    List<Feed> results = new LinkedList<>();    Document document = null;    try {        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();        DocumentBuilder builder = factory.newDocumentBuilder();        //document = builder.parse(IOUtils.toInputStream(this.aggregatedRssString);        InputStream stream = new ByteArrayInputStream(this.aggregatedRssString.getBytes());        document = builder.parse(stream);  //TODO HERE We have the Problem        stream.close();        //Normalize the XML Structure; It's just too important !!        document.getDocumentElement().normalize();    } catch (ParserConfigurationException | SAXException | IOException e) {        e.printStackTrace();    }    //Here comes the root node    if (document != null) {      //Element root = document.getDocumentElement();        //Get all        NodeList nList = document.getElementsByTagName("item");        for (int i = 0; i < nList.getLength(); i++) {            Node node = nList.item(i);            Element ele = (Element) node;            Feed feed = new Feed();            feed.setDate(ele.getElementsByTagName("dc:date").item(0).getTextContent());            feed.setDescription(ele.getElementsByTagName("description").item(0).getTextContent());            feed.setLink(ele.getElementsByTagName("link").item(0).getTextContent());            feed.setSubject(ele.getElementsByTagName("title").item(0).getTextContent());            feed.setId(getIdCounter());  //set the id. This increments also        /* now the searching ... */            if (feed.getSubject().toLowerCase().contains(keyword) || feed.getDescription().toLowerCase().contains(keyword))                results.add(feed);        }    }    return results;}

I can't figure out what should be wrong with the line document = builder.parse(stream); //TODO HERE We have the Problem ?

What strikes me here is that when testing it with a junit-test, all goes well:

@Testpublic void searchTest() throws Exception {    List<Feed> results = rssAggregator.searchAggregatedFeeds("a");    System.out.println("Hits: "+ results.size());    List<Feed> results2 = rssAggregator.searchAggregatedFeeds("z");    System.out.println("Hits: "+ results2.size());    List<Feed> results3 = rssAggregator.searchAggregatedFeeds("x");    System.out.println("Hits: "+ results3.size());}

resulting as expected:Image may be NSFW.
Clik here to view.

... while calling it from the cyclic job doesn't:

    List<Feed> allResults = new LinkedList<>();    /* for each WORD search the aggregatedfeed for matches and add them to allResults */    configBean.words.forEach(w -> {        System.out.println("current searched for Word: "+ w);        List<Feed> wResults = aggregator.searchAggregatedFeeds(w);  // :(        allResults.addAll(wResults);    });

Question: why does the junit-test work, while the call from within the application doesn't? The aggregated feeds are exactly the same.