Program: 178506
Project: 178506
Buggy source:
@Override public void onKeyDown(KeyDownEvent event){
  final int keyCode=event.getNativeKeyCode();
  log.fine("String_Node_Str" + keyCode + "String_Node_Str"+ event.getNativeEvent().getKeyCode());
  Selection selection=getTextArea().getDocument().getSelection();
  if (selection.getRangeCount() > 0) {
    Range range=selection.getRangeAt(0);
    OperationTarget t=getTarget(range);
    log.fine("String_Node_Str" + t);
    int pos=t.getStartOffset();
    List<Integer> path=t.getStartContainer();
    TreeOperation op=null;
    if (keyCode == 8) {
      if (pos == 0) {
        if (isNoteworthyPath(path)) {
          op=new TreeMergeParagraph(clientJupiter.getSiteId(),path.get(0),1,1);
          op.setPath(convertPath(path));
        }
      }
 else {
        pos=pos - 1;
        op=new TreeDeleteText(clientJupiter.getSiteId(),pos,convertPath(path));
      }
    }
 else     if (keyCode == 46) {
      Text textNode=Text.as(TreeHelper.getChildNodeFromLocator(bodyNode,convertPath(t.getStartContainer())));
      if ((t.getStartOffset() == t.getEndOffset()) && (textNode.getLength() == t.getStartOffset())) {
        path.set(0,path.get(0) + 1);
        op=new TreeMergeParagraph(clientJupiter.getSiteId(),path.get(0),1,1);
      }
 else {
        op=new TreeDeleteText(clientJupiter.getSiteId(),pos,convertPath(path));
      }
    }
 else     if (keyCode == 13) {
      if (pos == 0 && !isNoteworthyPath(path.subList(1,path.size()))) {
        op=new TreeNewParagraph(clientJupiter.getSiteId(),path.get(0));
        op.setPath(convertPath(path));
      }
 else {
        op=new TreeInsertParagraph(clientJupiter.getSiteId(),pos,convertPath(path));
      }
    }
    if (op != null) {
      clientJupiter.generate(op);
    }
  }
}

Fixed version (ground truth):
@Override public void onKeyDown(KeyDownEvent event){
  final int keyCode=event.getNativeKeyCode();
  log.fine("String_Node_Str" + keyCode + "String_Node_Str"+ event.getNativeEvent().getKeyCode());
  Selection selection=getTextArea().getDocument().getSelection();
  if (selection.getRangeCount() > 0) {
    Range range=selection.getRangeAt(0);
    OperationTarget t=getTarget(range);
    log.fine("String_Node_Str" + t);
    int pos=t.getStartOffset();
    List<Integer> path=t.getStartContainer();
    TreeOperation op=null;
    if (keyCode == 8) {
      if (pos == 0) {
        if (isNoteworthyPath(path)) {
          op=new TreeMergeParagraph(clientJupiter.getSiteId(),path.get(0),1,1);
          op.setPath(convertPath(path));
        }
      }
 else {
        pos=pos - 1;
        op=new TreeDeleteText(clientJupiter.getSiteId(),pos,convertPath(path));
      }
    }
 else     if (keyCode == 46) {
      Text textNode=Text.as(TreeHelper.getChildNodeFromLocator(bodyNode,convertPath(t.getStartContainer())));
      if ((t.getStartOffset() == t.getEndOffset()) && (textNode.getLength() == t.getStartOffset())) {
        path.set(0,path.get(0) + 1);
        op=new TreeMergeParagraph(clientJupiter.getSiteId(),path.get(0),1,1);
      }
 else {
        op=new TreeDeleteText(clientJupiter.getSiteId(),pos,convertPath(path));
      }
    }
 else     if (keyCode == 13) {
      if (pos == 0 && !isNoteworthyPath(path.subList(1,path.size()))) {
        op=new TreeNewParagraph(clientJupiter.getSiteId(),pos);
        op.setPath(convertPath(path));
      }
 else {
        op=new TreeInsertParagraph(clientJupiter.getSiteId(),pos,convertPath(path));
      }
    }
    if (op != null) {
      clientJupiter.generate(op);
    }
  }
}