protected function onFileChanged()
    {
        $this->firstLinesRaw = null;
        $this->firstLines = null;
        if ($this->separatorWasDetected) {
            $this->separator = '';
            $this->separatorWasDetected = false;
        }
        if ($this->headerWasDetected) {
            $this->setHeader([]);
            $this->headerWasDetected = false;
        }
    }