old_contents: export DevTools from './DevTools/DevTools';
  export Board from './Board/Board';
  export DraggableCard from './DraggableCard/DraggableCard';
  export MinionDropTarget from './MinionDropTarget/MinionDropTarget';
  
new_contents: export DevTools from './DevTools/DevTools';
  export Board from './Board/Board';
  export BoardSideDropTarget from './BoardSideDropTarget/BoardSideDropTarget';
  export DraggableCard from './DraggableCard/DraggableCard';
  export MinionDropTarget from './MinionDropTarget/MinionDropTarget';
  
subject: Add BoardSideDropTarget to containers index