--- /dev/null
+<?php
+
+namespace Drupal\serialization\Normalizer;
+
+/**
+ * Converts list objects to arrays.
+ *
+ * Ordinarily, this would be handled automatically by Serializer, but since
+ * there is a TypedDataNormalizer and the Field class extends TypedData, any
+ * Field will be handled by that Normalizer instead of being traversed. This
+ * class ensures that TypedData classes that also implement ListInterface are
+ * traversed instead of simply returning getValue().
+ */
+class ListNormalizer extends NormalizerBase {
+
+ /**
+ * The interface or class that this Normalizer supports.
+ *
+ * @var string
+ */
+ protected $supportedInterfaceOrClass = 'Drupal\Core\TypedData\ListInterface';
+
+ /**
+ * {@inheritdoc}
+ */
+ public function normalize($object, $format = NULL, array $context = []) {
+ $attributes = [];
+ foreach ($object as $fieldItem) {
+ $attributes[] = $this->serializer->normalize($fieldItem, $format, $context);
+ }
+ return $attributes;
+ }
+
+}