private function getHeaderLine($columnMetrics)
    {
        foreach ($columnMetrics as $index => $value) {
            if (in_array($value, $this->unsupportedColumns)) {
                unset($columnMetrics[$index]);
            }
        }

        if ($this->translateColumnNames) {
            $columnMetrics = $this->translateColumnNames($columnMetrics);
        }

        foreach ($columnMetrics as &$value) {
            $value = $this->formatValue($value);
        }

        return implode($this->separator, $columnMetrics);
    }