Wim Leers
--- a/core/lib/Drupal/Core/Config/Schema/Mapping.php
+++ b/core/lib/Drupal/Core/Config/Schema/Mapping.php

+  /**
+   * {@inheritdoc}
+   */
+  public function getCanonicalRepresentation(): array {
+    $representation = [];
+
+    // Mapping keys should be ordered however the data definition says.
+    // Note: this specifically does NOT use required/optional keys, because this
+    // MUST work even on invalid data (i.e. when required keys are missing).
+    $ordered_mapping_keys = $this->getValidKeys();
+
+    // Generate a representation of this mapping:
+    // 1. defer to each value's own canonical representation
+    // (::getElements() respects the stored order in $this->value, not the
+    // schema order)
--- a/core/lib/Drupal/Core/TypedData/Plugin/DataType/BooleanData.php
+++ b/core/lib/Drupal/Core/TypedData/Plugin/DataType/BooleanData.php
   * {@inheritdoc}
   */
  public function getCastedValue() {
+    if ($this->value === NULL) {
+      return NULL;
+    }
+