title: Error during Table cache update in vaadin
body: <p>MY code is:</p>
  
  <pre><code>   BeanItemContainer&lt;TimeCardBean&gt; results = new BeanItemContainer&lt;TimeCardBean&gt; (TimeCardBean.class);
          for (TimeCardBean bean : beans) {
              results.addBean(bean);
          }
        table.setContainerDataSource(results);
        table.addGeneratedColumn("function",new ColumnGenerator(){
        public Object generateCell(final Table source, final Object itemId, final Object columnId) {
        Byte timecardSeq=
       (Byte)source.addItem(itemId).getItemProperty("timeCardSeq").getValue();
  
       Button btnChange= new Button("Change", new ClickListener() {
       public void buttonClick(final ClickEvent event) {
       TimeCardEditDialog editDialog = new TimeCardEditDialog(viewService);
                              editDialog.init(timecardSeq);
       }
      });
     return btnChange;
  }
  </code></pre>
  
  <p><strong><em>I get the following error:</em></strong></p>
  
  <blockquote>
    <p>com.vaadin.ui.Table$CacheUpdateException: Error during Table cache update. Additional causes not shown.
        at com.vaadin.ui.Table.maybeThrowCacheUpdateExceptions(Table.java:1716)
        at com.vaadin.ui.Table.refreshRenderedCells(Table.java:1705)
        at com.vaadin.ui.Table.refreshRowCache(Table.java:2638)
        at com.vaadin.ui.Table.addGeneratedColumn(Table.java:4404)</p>
  </blockquote>
  
  <p>Hope you got when I want to express and can anyone tell me about to do this?</p>