Can you please advise me how to define a validator form, where I have the option to attach multiple files and only the mimetype image/jpeg is allowed.
For one file is:
$validator
->allowEmptyFile('image_teaser')
->requirePresence('image_teaser', 'create')
->uploadedFile('image_teaser', [
'types' => [
'image/jpeg',
],
],".jpg");