replaced other depracated functions like drupal_get_path

includes/doi.inc

@@ -157,8 +157,8 @@ function upei_roblib_ill_doi_name_from_url($doi_url) {
  * @param bool parse
  *   parse the doi to remove prefix and whitespace etc.
  *
- * @return object
+ * @return \Psr\Http\Message\ResponseInterface
- *   An object as provided by drupal_http_request().
+ *   An object as provided by \Drupal::httpClient()->get().
  */
 function upei_roblib_ill_doi_load($doi, $parse = TRUE) {
   // Allows for $id to pass a DOI url string or the DOI name.

upei_roblib_ill.install

@@ -6,7 +6,7 @@
 
 
 function upei_roblib_ill_update_7100() {
-  db_change_field('upei_roblib_ill_request', 'isbn', 'isbn',
+  \Drupal::database()->schema()->changeField('upei_roblib_ill_request', 'isbn', 'isbn',
     array(
       'description' => 'book isbn',
       'type' => 'varchar',

upei_roblib_ill.module

@@ -20,7 +20,7 @@ function upei_roblib_ill_doi_callback($form, &$form_state) {
 function upei_roblib_ill_views_api() {
   return [
     'api' => 3,
-    'path' => drupal_get_path('module', 'upei_roblib_ill') . '/views',
+    'path' => \Drupal::service('extension.list.module')->getPath('upei_roblib_ill') . '/views',
   ];
 }