public function addTestCustomAttributes(ModuleDataSetupInterface $setup, ModuleContextInterface $context) { $eavSetup = $this->eavSetupFactory->create(['setup' => $setup]); $eavSetup->addAttribute( MagentoCatalogModelProduct::ENTITY, 'test_courses', [ 'type' => 'varchar', 'backend' => 'MagentoEavModelEntityAttributeBackendArrayBackend', 'frontend' => '', 'label' => 'Select the Course', 'note' => '', 'input' => 'multiselect', 'frontend_class' => '', 'source' => TestCourseModelConfigSourceGroupMultiselect::class, 'global' => MagentoEavModelEntityAttributeScopedAttributeInterface::SCOPE_STORE, 'visible' => true, 'required' => […]