only in patch2:
unchanged:
--- a/commerce.services.yml
+++ b/commerce.services.yml
@@ -64,3 +64,10 @@ services:
   plugin.manager.commerce_entity_trait:
     class: Drupal\commerce\EntityTraitManager
     arguments: ['@container.namespaces', '@cache.discovery', '@module_handler', '@commerce.configurable_field_manager']
+  serializer.normalizer.object:
+    class: Drupal\commerce\Normalizer\ObjectAnyNormalizer
+    tags:
+    # This normalizer must be higher than serializer.normalizer.typed_data
+    # So setting priority as 0 here.
+    # @see \Drupal\commerce\Normalizer\ObjectAnyNormalizer::supportsNormalization
+      - { name: normalizer, priority: 0}
only in patch2:
unchanged:
--- /dev/null
+++ b/src/Normalizer/ObjectAnyNormalizer.php
@@ -0,0 +1,50 @@
+<?php
+
+namespace Drupal\commerce\Normalizer;
+
+use Drupal\commerce_order\Adjustment;
+use Drupal\serialization\Normalizer\NormalizerBase;
+
+/**
+ * Take place of TypedDataNormalizer when any's value is object.
+ *
+ * Here is for normalizing Adjustment. Delete this normalizer after
+ * https://www.drupal.org/node/2915705 be fixed in core.
+ */
+class ObjectAnyNormalizer extends NormalizerBase {
+
+  /**
+   * The interface or class that this Normalizer supports.
+   *
+   * @var string
+   */
+  protected $supportedInterfaceOrClass = 'Drupal\Core\TypedData\Plugin\DataType\Any';
+
+  /**
+   * {@inheritdoc}
+   */
+  public function supportsNormalization($data, $format = NULL) {
+    /* @var \Drupal\Core\TypedData\Plugin\DataType\Any $data */
+    if (parent::supportsNormalization($data, $format)) {
+      $value = $data->getValue();
+      if (isset($value) && is_object($value) && $value instanceof Adjustment) {
+        return TRUE;
+      }
+    }
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function normalize($object, $format = NULL, array $context = []) {
+    $value = $object->getValue();
+    // If the value is object or array, return the normalized result, object
+    // must be typed data or traversable to be normalizable.
+    if (isset($value) && (is_object($value) || is_array($value))) {
+      $value = $this->serializer->normalize($value, $format, $context);
+    }
+    return $value;
+  }
+
+}