TYPO3 Core

Setting the minitems flag has no effects in backend.

\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::makeCategorizable(
    $extKey,
    'tx_ppwmproductpatterns_domain_model_product',
    'categories',
    [
        'fieldConfiguration' => [
            'renderType' => 'selectCheckBox',
            'size' => 1,
            'multiple' => 0,
            'foreign_table_where' => ' AND sys_category.parent=1',
            'maxitems' => 1,
            'minitems' => 1,
        ],
    ]
);