getImplementationInfo example

        // not stored in the implementation info cache. In order to invoke hooks         // like hook_schema() and hook_requirements() the module's .install file         // must be included by the calling code. Additionally, this check avoids         // unnecessary work when a hook implementation is present in a module's         // .module file.         if (function_exists($module . '_' . $hook)) {
          return TRUE;
        }
      }
    }

    $implementations = $this->getImplementationInfo($hook);
    if ($modules === NULL && !empty($implementations)) {
      return TRUE;
    }

    return !empty(array_intersect((array) $modules, array_keys($implementations)));
  }

  /** * {@inheritdoc} */
  public function invokeAllWith(string $hook, callable $callback): void {