question: public static void mergeNodeChildren ( TreeNode node ) { DefaultMutableTreeNode masterNode = ( DefaultMutableTreeNode ) node ; for ( int i = 0 ; i < masterNode . getChildCount ( ) ; i ++ ) { DefaultMutableTreeNode child = ( DefaultMutableTreeNode ) masterNode . getChildAt ( i ) ; if ( ! child . isLeaf ( ) ) { MergeHelpUtilities . mergeNodeChildren ( DEFAULT_MERGE_TYPE , child ) ; } } }
target:  Merge Node Children. Merge the children of a node according to the merging rules of the parent. Each subclass must implement this method