code: private void advanceIntoFile() throws XMLStreamException, JournalException {
          XMLEvent event = reader.nextEvent();
          if (!event.isStartDocument()) {
              throw new JournalException("Expecting XML document header, but event was '"
                      + event + "'");
          }
  
          event = reader.nextTag();
          if (!isStartTagEvent(event, QNAME_TAG_JOURNAL)) {
              throw new JournalException("Expecting FedoraJournal start tag, but event was '"
                      + event + "'");
          }
  
          String hash =
                  getOptionalAttributeValue(event.asStartElement(),
                                            QNAME_ATTR_REPOSITORY_HASH);
          checkRepositoryHash(hash);
      }
docs: Advance past the document header to the first JournalEntry.