Gaël Gosset
--- a/core/modules/jsonapi/src/JsonApiResource/ResourceObject.php
+++ b/core/modules/jsonapi/src/JsonApiResource/ResourceObject.php
   */
  protected $language;

+  /**
+   * The resource object's metadata.
+   *
+   * @var array
+   */
+  protected $meta;
-  protected $meta;
+  protected array $meta;
--- a/core/modules/jsonapi/src/JsonApiResource/ResourceObject.php
+++ b/core/modules/jsonapi/src/JsonApiResource/ResourceObject.php
    // entity system
    // @see \Drupal\Core\Entity\EntityBase::language()
    $this->language = $language ?: new Language(['id' => LanguageInterface::LANGCODE_NOT_SPECIFIED]);
+    $this->meta = $meta;
+  }
+
+  /**
+   * Returns a copy of the given ResourceObject with the given arity.
+   *
+   * @param int $arity
+   *   The new arity; must be a non-negative integer.
-   *   The new arity; must be a non-negative integer.
+   *   The new arity, must be a non-negative integer.
--- a/core/modules/jsonapi/src/JsonApiResource/ResourceObject.php
+++ b/core/modules/jsonapi/src/JsonApiResource/ResourceObject.php
+   * @param int $arity
+   *   The new arity; must be a non-negative integer.
+   *
+   * @return static
+   *   A newly created ResourceObject with the given arity, otherwise
+   *   the same.
+   */
+  public function withArity(int $arity): ResourceObject {
+    if ($this->resourceType->isVersionable()) {
+      $versionIdentifier = str_replace('id:', '', $this->getVersionIdentifier());
+    }
+    else {
+      $versionIdentifier = NULL;
+    }
+
+    return new static(
--- a/core/modules/jsonapi/tests/src/Functional/ActionTest.php
+++ b/core/modules/jsonapi/tests/src/Functional/ActionTest.php
        'links' => [
          'self' => ['href' => $self_url],
        ],
+        'meta' => [