diff -u b/core/lib/Drupal/Core/TypedData/Plugin/DataType/Map.php b/core/lib/Drupal/Core/TypedData/Plugin/DataType/Map.php
--- b/core/lib/Drupal/Core/TypedData/Plugin/DataType/Map.php
+++ b/core/lib/Drupal/Core/TypedData/Plugin/DataType/Map.php
@@ -156,9 +156,9 @@
    */
   public function getProperties($include_computed = FALSE) {
     $properties = [];
-    $PropertyDefinitions = $this->definition->getPropertyDefinitions();
-    if (!empty($PropertyDefinitions)) {
-      foreach ($PropertyDefinitions as $name => $definition) {
+    $property_definitions = $this->definition->getPropertyDefinitions();
+    if (!empty($property_definitions)) {
+      foreach ($property_definitions as $name => $definition) {
         if ($include_computed || !$definition->isComputed()) {
           $properties[$name] = $this->get($name);
         }