code: private void updateBeanValueForRowRenderer(final WTableRowRenderer rowRenderer,
  			final UIContext rowContext,
  			final Class<? extends WComponent> expandRenderer) {
  
  		Container expandWrapper = (Container) rowRenderer.
  				getExpandedTreeNodeRenderer(expandRenderer);
  		if (expandWrapper == null) {
  			return;
  		}
  
  		// The actual component is wrapped in a renderer wrapper, so we have to fetch it from that
  		WComponent expandInstance = expandWrapper.getChildAt(0);
  
  		UIContextHolder.pushContext(rowContext);
  		try {
  			// Will apply updates to the "bean" returned by the model for this expanded renderer (ie
  			// getValueAt(rowIndex, -1))
  			WebUtilities.updateBeanValue(expandInstance);
  		} finally {
  			UIContextHolder.popContext();
  		}
  
  	}
docs: Update the expandable row renderer.
  
  @param rowRenderer the table row renderer
  @param rowContext the row context
  @param expandRenderer the renderer for the expandable row.