Add magic methods for serialization

Makes this package usable with PHP 7.4 and higher.

src/Surfnet/StepupRa/RaBundle/Security/Authentication/Token/SamlToken.php

@@ -83,4 +83,46 @@ public function unserialize($serialized)
 
         parent::unserialize($parent);
     }
+
+    /**
+     * Returns all the necessary state of the object for serialization purposes.
+     *
+     * There is no need to serialize any entry, they should be returned as-is.
+     * If you extend this method, keep in mind you MUST guarantee parent data is present in the state.
+     * Here is an example of how to extend this method:
+     * <code>
+     *     public function __serialize(): array
+     *     {
+     *         return [$this->childAttribute, parent::__serialize()];
+     *     }
+     * </code>
+     *
+     * @see __unserialize()
+     */
+    public function __serialize(): array
+    {
+        return [$this->assertion, $this->loa, parent::__serialize()];
+    }
+
+    /**
+     * Restores the object state from an array given by __serialize().
+     *
+     * There is no need to unserialize any entry in $data, they are already ready-to-use.
+     * If you extend this method, keep in mind you MUST pass the parent data to its respective class.
+     * Here is an example of how to extend this method:
+     * <code>
+     *     public function __unserialize(array $data): void
+     *     {
+     *         [$this->childAttribute, $parentData] = $data;
+     *         parent::__unserialize($parentData);
+     *     }
+     * </code>
+     *
+     * @see __serialize()
+     */
+    public function __unserialize(array $data): void
+    {
+        [$this->assertion, $this->loa, $parentData] = $data;
+        parent::__unserialize($parentData);
+    }
 }