/**
  * Returns visibility state of the filter field for the given column ID
  *
  * @param columnId Column/Property ID of the filter field to query
  * @return true if filter is visible, false if it's hidden
  */
 public boolean isFilterFieldVisible(Object columnId) {
   Component component = columnIdToFilterMap.get(columnId);
   if (component != null) {
     return component.isVisible();
   }
   return false;
 }