If you need to import pages from another system to Drupal 8 you can get inspired by following code.
Site structure is defined in XML file. Following example will create two pages with menu links and one independent menu link pointing to /atlas URL.

pageProgrammingprogramming.htmltrueProgrammingProgramming-45/programmingpageDrupal 8 - Basic HTML Blockdrupal8-html-block.htmltrueDrupal 8 Basic HTML BlockDrupal 8 Basic HTML Block/programming-50/drupal8-html-blocklinkAtlastrueAtlasAtlas-48/atlas

XML file is processed in ImportForm controller.

namespace Drupal\page_importer\Form;

use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;
use Drupal\node\NodeInterface;
use Drupal\Core\StringTranslation\StringTranslationTrait;
use Drupal\Core\Url;
use Drupal\menu_link_content\Entity\MenuLinkContent;
use Drupal\microatlas\Service\AtlasTranslator;
use Symfony\Component\HttpFoundation\RedirectResponse;
use Drupal\microatlas\Service\Drupal\microatlas\Service;
use Drupal\microatlas\Model\Category;
use Drupal\microatlas\Service\AtlasRepository;
use Drupal\Core\File\FileSystem;
use Drupal\microatlas\Model\Entry;
use Drupal\microatlas\Model\Title;
use Drupal\microatlas\Model\Content;
use Drupal\microatlas\Model\Link;

class ImportForm extends FormBase {	
	
	function getFormID() {
		return 'page_importer';
	}
	
	public function buildForm(array $form, FormStateInterface $form_state) {
	
		$user = \Drupal::currentUser();		
		if ($user == null || $user->id () == 0) {
			return;
		}				
		
		$form ['path'] = array (
				'#type' => 'textfield',
				'#title' => $this->t('Path to xml'),
				'#default_value' => realpath(\Drupal::service('extension.list.module')->getPath('page_importer').'/data'),								
		);
		
		
		$form ['actions'] ['submit'] = array (
				'#type' => 'submit',
				'#value' => $this->t ( 'Submit' )  
		);							
		
		
		return $form;
	}
	
	public function validateForm(array &$form, FormStateInterface $form_state) {			
							
	}	
	
	public function submitForm(array &$form, FormStateInterface $form_state) {
		$categories_count = 0;
		$entries_count = 0;
		$path = $form_state->getValue("path");		
		$pages = simplexml_load_file($path.'/pages.xml');
				
	    $count = 0;
	    $menuItems = array();
		foreach ($pages->page as $page) {

			$parentId = "";
			if ($page->menu_parent_item != "") {
				$parentId = $menuItems[(string)$page->menu_parent_item]->getPluginId();
			}
			
			if ((string)$page->type == 'link') {
				$menuItem = MenuLinkContent::create([
						'title' => (string)$page->title,
						'link' => ['uri' => 'internal:'.(string)$page->url_alias],
						'menu_name' => 'main',
						'expanded' => 1,
						'parent' => $parentId,
				]);
				$menuItem->save();
				$menuItems[(string)$page->url_alias] = $menuItem;
			} else {			
				$new_page_values = array();
				$new_page_values['type'] = (string)$page->type;
				$new_page_values['title'] = $page->title;			
				$new_page_values['path'] = $page->url_alias;
				
				$body = file_get_contents($path.'/pages/'.$page->body_file);
				
				$new_page_values['body'] = array(
						'value' => $body,
						'format' => 'full_html',
				);
				$node = \Drupal::entityTypeManager()->getStorage('node')->create($new_page_values);
				//$node = entity_create('node', $new_page_values);		    
				$node->save();
				
				if ($page->provide_menu_link == 'true') {
					
					
					$menuItem = MenuLinkContent::create([
							'title' => (string)$page->title,
							'link' => ['uri' => 'internal:'.(string)$page->url_alias],
							'menu_name' => 'main',
							'expanded' => 1,
							'parent' => $parentId,
					]);
					$menuItem->save();
					$menuItems[(string)$page->url_alias] = $menuItem;					
				}
			}			
			$count = $count +1;			
		}						
				
		\Drupal::messenger()->addMessage(t('Number of created pages :@count.', array('@count' => $count)));
		
		
	}
}

If you need some help with importing pages to Drupal 8 or Alfresco CMS, you can contact me via email katalpa.cz@gmail.com.