if (t.getFragment() != null)
return;
// handle empty XML specially to avoid "" text nodes
if (t.getXML().isText() && t.getXML().asText().getString().isEmpty()) {
SequenceNode n = new SequenceNode(Collections.<Integer>emptyList(), s.getOrigin());
xg.addNode(n);
XMLGraphFragment f = new XMLGraphFragment(n, null, null, null);
t.setFragment(f);
} else {
XMLGraphFragment f = XMLGraphConverter.extend(xg, t.getXML(), XMLGraphConverter.GapConversion.CLOSED, true);
for (Map.Entry<String,String> en : f.getGapTypeMap().entrySet()) {