public void addChild(TreeStructure treeStruct){
  Util.notNull("treeStruct",treeStruct);
  if (children == null) {
    children=new ArrayList<TreeStructure>();
  }
  children.add(treeStruct);
}

public void addChild ( TreeStructure treeStruct ) { Util . notNull ( "treeStruct" , treeStruct ) ; if ( children == null ) { children = new ArrayList < TreeStructure > ( ) ; } children . add ( treeStruct ) ; }
adds treestruct as a child of this treestructure instance .
