public void collapse(GraphNode master,Collection<GraphNode> picked,boolean erase,Object author){
  collapser.collapse(master,picked,erase);
  fireCollapseChanged(Collections.singleton(collapser.getCollapseData(master)),CollapseData.EMPTY_LIST,author);
}

public void collapse ( GraphNode master , Collection < GraphNode > picked , boolean erase , Object author ) { collapser . collapse ( master , picked , erase ) ; fireCollapseChanged ( Collections . singleton ( collapser . getCollapseData ( master ) ) , CollapseData . EMPTY_LIST , author ) ; }
collapse a set of nodes under a specific master node .
