private function getMetrics()
    {
        $metrics = [
            $this->metricFactory->create(
                ['name' => 'unique_sessions', 'field' => 'session.uid', 'type' => MetricInterface::TYPE_CARDINALITY]
            ),
            $this->metricFactory->create(
                ['name' => 'unique_visitors', 'field' => 'session.vid', 'type' => MetricInterface::TYPE_CARDINALITY]
            ),
            $this->metricFactory->create(
                ['name' => 'spellcheck_usage', 'field' => 'page.search.is_spellchecked', 'type' => MetricInterface::TYPE_STATS]
            ),
        ];

        return $metrics;
    }
private function getMetrics()
    {
        $metrics = [
            $this->metricFactory->create(
                ['name' => 'unique_sessions', 'field' => 'session.uid', 'type' => MetricInterface::TYPE_CARDINALITY]
            ),
            $this->metricFactory->create(
                ['name' => 'unique_visitors', 'field' => 'session.vid', 'type' => MetricInterface::TYPE_CARDINALITY]
            ),
            $this->metricFactory->create(
                ['name' => 'spellcheck_usage', 'field' => 'page.search.is_spellchecked', 'type' => MetricInterface::TYPE_STATS]
            ),
        ];

        return $metrics;
    }
private function getMetrics ( ) { $ metrics = [ $ this -> metricFactory -> create ( [ 'name' => 'unique_sessions' , 'field' => 'session.uid' , 'type' => MetricInterface :: TYPE_CARDINALITY ] ) , $ this -> metricFactory -> create ( [ 'name' => 'unique_visitors' , 'field' => 'session.vid' , 'type' => MetricInterface :: TYPE_CARDINALITY ] ) , $ this -> metricFactory -> create ( [ 'name' => 'spellcheck_usage' , 'field' => 'page.search.is_spellchecked' , 'type' => MetricInterface :: TYPE_STATS ] ) , ] ; return $ metrics ; }
Return metrics aggregations to apply to the main bucket aggregation

@return array
Return metrics aggregations to apply to the main bucket aggregation