Index.php

<?php

namespace Dotdigitalgroup\Email\Controller\Adminhtml\Wishlist;

class Index extends \Magento\Backend\App\Action
{
    /**
     * Authorization level of a basic admin session
     *
     * @see _isAllowed()
     */
    const ADMIN_RESOURCE = 'Dotdigitalgroup_Email::wishlist';

    /**
     * @var \Magento\Framework\View\Result\PageFactory
     */
    private $resultPageFactory;

    /**
     * Index constructor.
     *
     * @param \Magento\Backend\App\Action\Context $context
     * @param \Magento\Framework\View\Result\PageFactory $resultPageFactory
     */
    public function __construct(
        \Magento\Backend\App\Action\Context $context,
        \Magento\Framework\View\Result\PageFactory $resultPageFactory
    ) {
        parent::__construct($context);
        $this->resultPageFactory = $resultPageFactory;
    }

    /**
     * Index action.
     *
     * @return \Magento\Backend\Model\View\Result\Page
     */
    public function execute()
    {
        /** @var \Magento\Backend\Model\View\Result\Page $resultPage */
        $resultPage = $this->resultPageFactory->create();
        $resultPage->setActiveMenu('Dotdigitalgroup_Email::wishlist');
        $resultPage->addBreadcrumb(__('Wishlists'), __('Wishlists'));
        $resultPage->getConfig()->getTitle()->prepend(__('Wishlist Report'));

        return $resultPage;
    }
}