code: private final String indexTagId(String tagId) {
          DataGridTagModel dataGridTagModel = lookupDataGridTagModel();
          assert dataGridTagModel != null;
  
          int index = dataGridTagModel.getCurrentIndex();
          assert index >= 0;
  
          return tagId + index;
      }
docs: Generate an indexed tag ID.  This method will use the
  {@link org.apache.beehive.netui.databinding.datagrid.api.rendering.DataGridTagModel#getCurrentIndex()} method
  to scope a given name to a particular row in the data grid.
  @param tagId the base tag id
  @return an index-scoped tag id