context definition

app/docroot/modules/custom/mymodule/mymodule.module

@@ -186,9 +186,11 @@ function mymodule_node_access(\Drupal\Core\Entity\EntityInterface $node, $operat
   }
 }
 
-function mymodule_node_presave($node) {
+/**
+ * Implements hook_node_insert()
+ */
+function mymodule_node_insert(Drupal\Core\Entity\EntityInterface $node) {
   $user = Drupal::currentUser();
-
   $user_roles = $user->getRoles();
   $isRedactor = false;
   foreach ($user_roles as $role) {
@@ -198,12 +200,6 @@ function mymodule_node_presave($node) {
   }
   if ($isRedactor) {
     if ($node->hasField('field_editor')) {
-      $editors = $node->get("field_editor")->referencedEntities();
-      foreach ($editors as $editor) {
-        if ($editor->id() == $user->id()) {
-          return true;
-        }
-      }
       $node->field_editor[] = $user->id();
     }
   }

app/docroot/modules/custom/mymodule/src/Plugin/Block/ContextDefinition.php

+<?php
+
+namespace Drupal\mymodule\Plugin\Block;
+
+use Drupal\Core\Block\BlockBase;
+
+/**
+ * Provides
+ *
+ * @Block(
+ *   id = "test_context_definition",
+ *   admin_label = @Translation("Test block with context_definition"),
+ *   context_definitions = {
+ *     "node" = @ContextDefinition("entity:node", required = FALSE, label = @Translation("Node")),
+ *     "term" = @ContextDefinition("entity:taxonomy_term", required = FALSE, label = @Translation("Term")),
+ *   }
+ * )
+ */
+
+class ContextDefinition extends BlockBase {
+
+  public function build() {
+    $node = $this->getContextValue('node');
+    $term = $this->getContextValue('term');
+
+    empty($node) ? $entiy = $term : $entiy = $node;
+    empty($node) ? $entiy_type_id = 'taxonomy_term' : $entiy_type_id  = 'node';
+    $build = \Drupal::entityTypeManager()->getViewBuilder($entiy_type_id)->view($entiy, 'teaser');
+    $tags = $entiy->getCacheTags();
+    foreach ($tags as $tag) {
+      $build['#cache']['tags'][] = $tag;
+    }
+
+
+    return $build;
+  }
+}