diff --git a/src/Plugin/search_api/processor/AddHierarchy.php b/src/Plugin/search_api/processor/AddHierarchy.php
index 2ef94a2..b6f4bb8 100644
--- a/src/Plugin/search_api/processor/AddHierarchy.php
+++ b/src/Plugin/search_api/processor/AddHierarchy.php
@@ -14,7 +14,6 @@
 use Drupal\search_api\Item\FieldInterface;
 use Drupal\search_api\Plugin\PluginFormTrait;
 use Drupal\search_api\Processor\ProcessorPluginBase;
-use Drupal\search_api\Utility\FieldsHelperInterface;
 use Drupal\search_api\Utility\Utility;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
@@ -40,13 +39,6 @@ class AddHierarchy extends ProcessorPluginBase implements PluginFormInterface {
   protected $entityTypeManager;
 
   /**
-   * The fields helper.
-   *
-   * @var \Drupal\search_api\Utility\FieldsHelperInterface|null
-   */
-  protected static $fieldsHelper;
-
-  /**
    * {@inheritdoc}
    */
   public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
@@ -54,32 +46,11 @@ public static function create(ContainerInterface $container, array $configuratio
     $processor = parent::create($container, $configuration, $plugin_id, $plugin_definition);
 
     $processor->setEntityTypeManager($container->get('entity_type.manager'));
-    static::setFieldsHelper($container->get('search_api.fields_helper'));
 
     return $processor;
   }
 
   /**
-   * Retrieves the fields helper.
-   *
-   * @return \Drupal\search_api\Utility\FieldsHelperInterface
-   *   The fields helper.
-   */
-  public static function getFieldsHelper() {
-    return static::$fieldsHelper ?: \Drupal::service('search_api.fields_helper');
-  }
-
-  /**
-   * Sets the fields helper.
-   *
-   * @param \Drupal\search_api\Utility\FieldsHelperInterface $fields_helper
-   *   The new fields helper.
-   */
-  public static function setFieldsHelper(FieldsHelperInterface $fields_helper) {
-    static::$fieldsHelper = $fields_helper;
-  }
-
-  /**
    * Retrieves the entity type manager service.
    *
    * @return \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
@@ -139,7 +110,9 @@ protected static function getHierarchyFields(IndexInterface $index) {
         $properties[''] = $definition;
         foreach ($properties as $property) {
           $property_label = $property->getLabel();
-          $property = static::$fieldsHelper->getInnerProperty($property);
+          $property = \Drupal::getContainer()
+            ->get('search_api.fields_helper')
+            ->getInnerProperty($property);
           if ($property instanceof EntityDataDefinitionInterface) {
             $options = self::findHierarchicalProperties($property, $property_label);
             if ($options) {
@@ -182,11 +155,12 @@ protected static function getHierarchyFields(IndexInterface $index) {
   protected static function findHierarchicalProperties(EntityDataDefinitionInterface $property, $property_label) {
     $entity_type_id = $property->getEntityTypeId();
     $options = array();
+    $fields_helper = \Drupal::getContainer()->get('search_api.fields_helper');
 
     // Check properties for potential hierarchy.
     foreach ($property->getPropertyDefinitions() as $name_2 => $property_2) {
       $property_2_label = $property_2->getLabel();
-      $property_2 = static::$fieldsHelper->getInnerProperty($property_2);
+      $property_2 = $fields_helper->getInnerProperty($property_2);
       if ($property_2 instanceof EntityDataDefinitionInterface) {
         if ($property_2->getEntityTypeId() == $entity_type_id) {
           $options["$entity_type_id-$name_2"] = Html::escape($property_label . ' » ' . $property_2_label);
@@ -194,7 +168,7 @@ protected static function findHierarchicalProperties(EntityDataDefinitionInterfa
       }
       elseif ($property_2 instanceof ComplexDataDefinitionInterface) {
         foreach ($property_2->getPropertyDefinitions() as $property_3) {
-          $property_3 = static::$fieldsHelper->getInnerProperty($property_3);
+          $property_3 = $fields_helper->getInnerProperty($property_3);
           if ($property_3 instanceof EntityDataDefinitionInterface) {
             if ($property_3->getEntityTypeId() == $entity_type_id) {
               $options["$entity_type_id-$name_2"] = Html::escape($property_label . ' » ' . $property_2_label);