protected function initColumns()
    {
        $returnValue = (bool) false;

		$excludedProperties = (is_array($this->options) && isset($this->options['excludedProperties']))?$this->options['excludedProperties']:array();
		$columnNames = (is_array($this->options) && isset($this->options['columnNames']))?$this->options['columnNames']:array();
		
		
		$processProperties = array(
            OntologyRdfs::RDFS_LABEL					=> __('Label'),
            ResultService::DELIVERY_CLASS_URI	=> __('Delivery'),
            ResultService::SUBJECT_CLASS_URI	=> __('Test taker'),
			OntologyRdf::RDF_TYPE                	=> __('Class')
		);
		
		foreach($processProperties as $processPropertyUri => $label){
			if(!isset($excludedProperties[$processPropertyUri])){
				$column = $this->grid->addColumn($processPropertyUri, $label);
               
			}
		}

		$this->grid->setColumnsAdapter(
			array_keys($processProperties),
			new tao_helpers_grid_Cell_ResourceLabelAdapter()
		);

        return (bool) $returnValue;
    }