--- /dev/null
+/**
+ * Implements hook_field_widget_WIDGET_TYPE_form_alter().
+ */
+function {{ machine_name }}_field_widget_WIDGET_TYPE_form_alter(&$element, \Drupal\Core\Form\FormStateInterface $form_state, $context) {
+ // Code here will only act on widgets of type WIDGET_TYPE. For example,
+ // hook_field_widget_mymodule_autocomplete_form_alter() will only act on
+ // widgets of type 'mymodule_autocomplete'.
+ $element['#autocomplete_route_name'] = 'mymodule.autocomplete_route';
+}