non uniform rowSpans in a grid produces extra column

<zk>
	<zscript><![CDATA[
		import java.util.*;
		
		import org.zkoss.zk.ui.Component;
		import org.zkoss.zk.ui.Executions;
		import org.zkoss.zk.ui.util.GenericForwardComposer;
		import org.zkoss.zul.*;
		
		import java.util.logging.Level;
		import java.util.logging.Logger;
		
		public class MyComposer extends GenericForwardComposer {
			public void doBeforeComposeChildren(Component comp) throws Exception {
				super.doBeforeComposeChildren(comp);
				
				comp.setAttribute("model", createModel());
				comp.setAttribute("renderer", new MyRowRenderer());
			}
			
			static Logger theLog = Logger.getLogger("com.ArivX.SRP");
		
			static HashMap AHash = new HashMap();
			static HashMap SAHash = new HashMap();
			Integer ACount = new Integer(0);
			
			private ListModel createModel() {
				List data = new ArrayList();
				
				List articleList = MyDAO.getArticle();
				for (int i = 0, j = articleList.size(); i < j; i++) {
					String article = (String) articleList.get(i);
					List subArticleList =  MyDAO.getSubArticle(article);
					
					for (int k = 0, l = subArticleList.size(); k < l; k++) {
						String subArticle = (String) subArticleList.get(k);
						List subSubArticleList =  MyDAO.getSubSubArticle(subArticle);
						
						for (int m = 0, n = subSubArticleList.size(); m < n; m++) {
							String subSubArticle = (String) subSubArticleList.get(m);
							data.add(new String[]{article, subArticle, subSubArticle});
							
							ACount++;
						}
						SAHash.put(subArticle, subSubArticleList.size());
					}
					AHash.put(article, ACount);
					ACount = new Integer(0);
				}
				return new ListModelList(data);
			}
		
		
			public static class MyDAO {
				public static List getArticle() {
					List list = new ArrayList();
					for (int i = 0; i < 2; i++)
						list.add("Article " + i);
					return list;
				}
				public static List getSubArticle(String article) {
					List list = new ArrayList();
					for (int i = 0; i < 3; i++)
						list.add("Sub" + article + i);
					return list;
				}
				public static List getSubSubArticle(String SubArticle) {
					List list = new ArrayList();
					//////////////////////////////////////
					// only code change is hear to add a random number of subarticles
					Random rg = new Random();
					int count = rg.nextInt(6) + 1; // Add 1 as zero is not allowed
					//int count = 5;
					//// done with code change
					for (int i = 0; i < count; i++)
						list.add("Sub" + SubArticle + i);
					return list;
				}
				
				public static int getTotalArticleCount(String article) {
					List subArticleList =  getSubArticle(article);
					int rowSpan = 0;
					for (int i = 0, j = subArticleList.size(); i < j; i++) {
						String subArticle = (String) subArticleList.get(i);
						rowSpan += getSubSubArticle(subArticle).size();
						//rowSpan += subArticle.length();
					}
					return rowSpan;
				}
			}
			
			public static class MyRowRenderer implements RowRendererExt, RowRenderer {
				private int index = 0;
				private String prevArticle = "", prevSubArticle="";
				private String[] curData;
				
				public Row newRow(Grid grid) {
					Row row = new Row();
					curData = getData(grid.getModel());
					boolean isNextArticle = !prevArticle.equals(curData[0]);
					boolean isNextSubArticle = !prevSubArticle.equals(curData[1]);
					
					Map arg = new HashMap();
					
					// first row of each SubArticle
					if (isNextSubArticle) {
						
						// first row of each article
						if (isNextArticle) {
							Cell cell = new Cell();
							prevArticle = curData[0];
							//cell.setRowspan(MyDAO.getTotalArticleCount(prevArticle));
							cell.setRowspan((Integer) AHash.get(prevArticle));
							theLog.info(prevArticle + " count is " + AHash.get(prevArticle));
							cell.appendChild(new Label(prevArticle));
							row.appendChild(cell);
						}
						
						prevSubArticle = curData[1];
						Cell cell = new Cell();
						cell.setRowspan(MyDAO.getSubSubArticle(prevSubArticle).size());
						cell.setRowspan((Integer) SAHash.get(prevSubArticle));
					    theLog.info(prevSubArticle + " count is " + SAHash.get(prevSubArticle));
						cell.appendChild(new Label(prevSubArticle));
						row.appendChild(cell);
					}
					return row;
				}
				private String[] getData(ListModel model) {
					if (model != null)
						return (String[]) model.getElementAt(index++);
					return null;
				}
				public Component newCell(Row row) {
					return new Label(curData[2].toString());
				}
				public int getControls() {
					return 0;
				}
				public void render(Row row, Object data) throws Exception {
				}
			}
		}
	]]></zscript>
	<window apply="MyComposer">
		<grid rowRenderer="${renderer}" model="${model}">
			<columns>
				<column label="Article"/>
				<column label="SubArticle"/>
				<column label="SubArticle"/>
			</columns>
		</grid>
	</window>
</zk>