Select File

You can take an example of file here.

// src/actions/import/do.php
$request = json_encode([
    'name' => 'Import',
    'files' => [
        [
            'fileName' => $fileName,
            'fileImportPage' => [
                'hasHeader' => true,
                'columnMappings' => [
                    [
                        'columnName' => 'First Name',
                        'propertyName' => 'firstname',
                        'columnObjectType' => 'CONTACT',
                    ],
                    [
                        'columnName' => 'Email',
                        'propertyName' => 'email',
                        'columnObjectType' => 'CONTACT',
                    ]
                ]
            ]
        ]
    ]
]);

$hubSpot->crm()->imports()->coreApi()->create($request, $fileName);