diff -u b/core/lib/Drupal/Core/Entity/ContentEntityInterface.php b/core/lib/Drupal/Core/Entity/ContentEntityInterface.php
--- b/core/lib/Drupal/Core/Entity/ContentEntityInterface.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityInterface.php
@@ -95,7 +95,7 @@
    *
    * @param bool $deep_serialization
    *   TRUE if deep serialization should be performed when the entity is being
-   *   serialized, FALSE otherwise. Defaults to TRUE.
+   *   serialized, FALSE otherwise.
    *
    * @return $this
    */
diff -u b/core/lib/Drupal/Core/Field/FieldItemBase.php b/core/lib/Drupal/Core/Field/FieldItemBase.php
--- b/core/lib/Drupal/Core/Field/FieldItemBase.php
+++ b/core/lib/Drupal/Core/Field/FieldItemBase.php
@@ -110,8 +110,7 @@
       // Iterate only over computed properties and include them, as the parent
       // method is not including them.
       foreach ($this->properties as $name => $property) {
-        $definition = $property->getDataDefinition();
-        if ($definition->isComputed()) {
+        if ($property->getDataDefinition()->isComputed()) {
           $value[$name] = $property->getValue();
         }
       }
@@ -129,7 +128,7 @@
    *   Whether to include computed properties as provided to ::getValue().
    *
    * @return bool
-   *   TRUE if computed properties have to be included. FALSE otherwise.
+   *   TRUE if computed properties have to be included, FALSE otherwise.
    *
    * @see ::getValue()
    */