6 files declare their use of DefaultModuleHelper

AbstractFormController.php in lib/Drupal/ooe/Form/AbstractFormController.php
AbstractFormController
AbstractPageController.php in lib/Drupal/ooe/Page/AbstractPageController.php
AbstractPageController
AbstractProject.php in lib/Drupal/ooe/Project/AbstractProject.php
AbstractProject
DefaultMenuItem.php in lib/Drupal/ooe/Menu/DefaultMenuItem.php
DefaultMenuItem
DemoOfMenuTabs.php in lib/Drupal/ooe/Demo/Tabs/DemoOfMenuTabs.php
DemoOfMenuTabs
MenuTabs.php in lib/Drupal/ooe/Menu/MenuTabs.php
MenuTabs