public function addMeasure(
        string $label,
        float $start,
        float $end,
        array $params      = [],
        ?string $collector = null
    ): void {
        $this->measures[] = [
            'label'          => $label,
            'start'          => $start,
            'relative_start' => $start - $this->requestStartTime,
            'end'            => $end,
            'relative_end'   => $end - $this->requestEndTime,
            'duration'       => $end - $start,
            'duration_str'   => $this->formatDuration($end - $start),
            'params'         => $params,
            'collector'      => $collector,
        ];
    }