Access datasources of custom controls

/**
 * getDatasource
 * Resolves a datasource from a custom control
 * 
 * @param componentId    id of the component containing the datasource
 * @param dsName    name of the datasource in the component
 * @author Sven Hasselbach
 */
 function getDatasource( componentId:String, dsName:String ) {
    try{
       var data:java.util.ArrayList = getComponent( componentId ).getAttributes().get("data");
       if( data == null )
          return null;
                    
       var it:java.util.Iterator = data.iterator();
       var obj = null;
       while( it.hasNext() ){
          obj = it.next();
          if( obj.getVar() == dsName )
             return obj;
       }
    }catch(e){
       print( e );
    }
}