Program: 75572
Project: 75572
Buggy source:
public Object execute(ExecutionEvent event) throws ExecutionException {
  SessionHandleAdapter.getInstance().getReportDesignHandle().getCommandStack().startTrans("String_Node_Str" + itemName);
  ExtendedItemHandle handle=null;
  handle=DesignElementFactory.getInstance().newExtendedItem(null,itemName);
  Map map=new HashMap();
  map.put(DesignerConstants.KEY_NEWOBJECT,handle);
  CreateCommand command=new CreateCommand(map);
  IEvaluationContext context=(IEvaluationContext)event.getApplicationContext();
  EditPart targetEditPart=(EditPart)context.getVariable("String_Node_Str");
  if (targetEditPart != null) {
    command.setParent(targetEditPart.getModel());
  }
 else {
    Object parentModel=UIUtil.getCurrentEditPart().getModel();
    if (parentModel instanceof DesignElementHandle) {
      DesignElementHandle parentHandle=(DesignElementHandle)parentModel;
      if (parentHandle.getDefn().isContainer()) {
        command.setParent(parentModel);
      }
 else {
        command.setParent(SessionHandleAdapter.getInstance().getReportDesignHandle());
      }
    }
 else {
      command.setParent(SessionHandleAdapter.getInstance().getReportDesignHandle());
    }
  }
  try {
    command.execute();
    SessionHandleAdapter.getInstance().getReportDesignHandle().getCommandStack().commit();
  }
 catch (  Exception e) {
    SessionHandleAdapter.getInstance().getReportDesignHandle().getCommandStack().rollback();
  }
  if (command.getParent() instanceof LibraryHandle) {
    HandleAdapterFactory.getInstance().getLibraryHandleAdapter().setCurrentEditorModel(handle,LibraryHandleAdapter.CREATE_ELEMENT);
  }
  return handle;
}

Fixed version (ground truth):
public Object execute(ExecutionEvent event) throws ExecutionException {
  SessionHandleAdapter.getInstance().getReportDesignHandle().getCommandStack().startTrans("String_Node_Str" + itemName);
  ExtendedItemHandle handle=null;
  handle=DesignElementFactory.getInstance().newExtendedItem(null,itemName);
  Map map=new HashMap();
  map.put(DesignerConstants.KEY_NEWOBJECT,handle);
  CreateCommand command=new CreateCommand(map);
  IEvaluationContext context=(IEvaluationContext)event.getApplicationContext();
  EditPart targetEditPart=(EditPart)context.getVariable("String_Node_Str");
  if (targetEditPart != null) {
    command.setParent(targetEditPart.getModel());
  }
 else {
    Object parentModel=DNDUtil.unwrapToModel(UIUtil.getCurrentEditPart().getModel());
    if (parentModel instanceof DesignElementHandle) {
      DesignElementHandle parentHandle=(DesignElementHandle)parentModel;
      if (parentHandle.getDefn().isContainer()) {
        command.setParent(parentModel);
      }
 else {
        command.setParent(SessionHandleAdapter.getInstance().getReportDesignHandle());
      }
    }
 else {
      command.setParent(SessionHandleAdapter.getInstance().getReportDesignHandle());
    }
  }
  try {
    command.execute();
    SessionHandleAdapter.getInstance().getReportDesignHandle().getCommandStack().commit();
  }
 catch (  Exception e) {
    SessionHandleAdapter.getInstance().getReportDesignHandle().getCommandStack().rollback();
  }
  if (command.getParent() instanceof LibraryHandle) {
    HandleAdapterFactory.getInstance().getLibraryHandleAdapter().setCurrentEditorModel(handle,LibraryHandleAdapter.CREATE_ELEMENT);
  }
  return handle;
}