PdfResponse::mpdfConfig does not allow fontDir

[JanKalach]

Mpdf can be created with config param fontDir.

$mpdf = new Mpdf([
    'tempDir' => $myTempDir,
    'fontDir' => [$myCustomFontDir],
    'fontData' =>[$myCustomFontData],
    'default_font' => 'poppins',
]);

When I add mpdfConfig with fontDir to PdfResponse

$PdfResponse = new PdfResponse();
$PdfResponse->mpdfConfig = [
    'tempDir' => $myTempDir,
    'fontdata' => [$myCustomFontData],
    'fontDir' => [$myCustomFontDir],
    'default_font' => 'poppins',
];
$mpdf = $PdfResponse->getMPDF();

I become error:
Cannot write to an undeclared property [Mpdf\Mpdf]::$fontDir
[Mpdf\Mpdf]::$fontDir is set as private property (vendor/mpdf/mpdf/src/Mpdf.php:283)

Using of Mpdf methods AddFontDirectory and AddFont do not apply changes, or font is not applied.
Fonts are used when the necessary configuration options are added to the object creation.

[radimvaculik]

@JanKalach This is my working solution:

        $mpdf = $this->pdf->getMPDF();
        $mpdf->fontdata += [
            'arial' => [
                'R' => 'arial-regular.ttf',
                'B' => 'arial-bold.ttf',
                'useOTL' => 0xff,
            ],
        ];
        $mpdf->AddFontDirectory(__DIR__ . '/font');
        $mpdf->AddFont('arial');
        $mpdf->SetFont('arial');