Julian Pustkuchen
--- a/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php
+++ b/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php
+   *
+   * @param string $entity_type_id
+   *   The entity type ID.
+   * @param string $id
+   *   The entity ID to add as a dependency.
+   *
+   * @return $this
+   *
+   * @throws \Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException
+   *   Thrown if the entity type is invalid.
+   * @throws \Drupal\Component\Plugin\Exception\PluginNotFoundException
+   *   Thrown if the entity type is invalid.
+   * @throws \Drupal\Core\Config\Entity\Exception\ConfigEntityDependencyException
+   *   Thrown if the entity does not exist.
+   */
+  protected function addConfigEntityDependency($entity_type_id, $id) {
-  protected function addConfigEntityDependency($entity_type_id, $id) {
+  protected function addConfigEntityDependency(string $entity_type_id, string $id): static {
--- a/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php
+++ b/core/tests/Drupal/Tests/Core/Config/Entity/ConfigEntityBaseUnitTest.php
    ];
  }

+  /**
+   * @covers ::addConfigEntityDependency
+   */
+  public function testAddConfigEntityDependency() {
-  public function testAddConfigEntityDependency() {
+  public function testAddConfigEntityDependency(): void {