diff --git a/core/lib/Drupal/Core/Entity/ContentEntityInterface.php b/core/lib/Drupal/Core/Entity/ContentEntityInterface.php
index ad38b9d3..97880fc 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityInterface.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityInterface.php
@@ -84,7 +84,7 @@ public function updateLoadedRevisionId();
    * will be serialized, but also the changes made on the referenced entities.
    *
    * Example usage:
-   * -Alter the title of a referenced entity and serialize the parent entity
+   * - Alter the title of a referenced entity and serialize the parent entity
    * through deep serialization in order to serialize the change made on the
    * referenced entity.
    * @code
diff --git a/core/lib/Drupal/Core/Field/EntityReferenceFieldItemList.php b/core/lib/Drupal/Core/Field/EntityReferenceFieldItemList.php
index f4fc99b..372cf2f 100644
--- a/core/lib/Drupal/Core/Field/EntityReferenceFieldItemList.php
+++ b/core/lib/Drupal/Core/Field/EntityReferenceFieldItemList.php
@@ -15,17 +15,14 @@ class EntityReferenceFieldItemList extends FieldItemList implements EntityRefere
    * {@inheritdoc}
    */
   public function getSerializationValue($deep_serialization) {
+    $values = parent::getSerializationValue($deep_serialization);
     if ($deep_serialization) {
-      $values = $this->getValue(TRUE);
       foreach ($values as $delta => $item_values) {
         if (isset($values[$delta]['entity']) && ($values[$delta]['entity'] instanceof ContentEntityInterface)) {
           $values[$delta]['entity']->setDeepSerialization(TRUE);
         }
       }
     }
-    else {
-      $values = parent::getSerializationValue($deep_serialization);
-    }
 
     return $values;
   }
diff --git a/core/lib/Drupal/Core/Field/FieldItemBase.php b/core/lib/Drupal/Core/Field/FieldItemBase.php
index 139463e..87fdb8c 100644
--- a/core/lib/Drupal/Core/Field/FieldItemBase.php
+++ b/core/lib/Drupal/Core/Field/FieldItemBase.php
@@ -104,8 +104,8 @@ protected function getSetting($setting_name) {
   public function getValue($include_computed = FALSE) {
     $value = parent::getValue();
 
-    // Include computed properties if the condition of
-    // ::includeComputedProperties() is fulfilled.
+    // Allow field types to opt-in or opt-out of including computed properties
+    // in certain cases.
     if ($this->includeComputedProperties($include_computed)) {
       // Iterate only over computed properties and include them, as the parent
       // method is not including them.
@@ -122,7 +122,7 @@ public function getValue($include_computed = FALSE) {
   /**
    * Checks if included properties have to be included.
    *
-   * Helper method for ::getValue() to check if included properties have to be
+   * Helper method for ::getValue() to check if included properties should be
    * included.
    *
    * @param bool $include_computed
@@ -130,8 +130,12 @@ public function getValue($include_computed = FALSE) {
    *
    * @return bool
    *   TRUE if computed properties have to be included. FALSE otherwise.
+   *
+   * @see ::getValue()
    */
   protected function includeComputedProperties($include_computed) {
+    // Even if computed fields were requested, do not attempt to compute
+    // anything if there are no actual values.
     return $include_computed && !$this->isEmpty();
   }
 
diff --git a/core/lib/Drupal/Core/Field/FieldItemListInterface.php b/core/lib/Drupal/Core/Field/FieldItemListInterface.php
index fd5cd68..898356f 100644
--- a/core/lib/Drupal/Core/Field/FieldItemListInterface.php
+++ b/core/lib/Drupal/Core/Field/FieldItemListInterface.php
@@ -275,13 +275,14 @@ public function equals(FieldItemListInterface $list_to_compare);
    * Gets the data value prepared for serialization.
    *
    * @param bool $deep_serialization
-   *   Whether a deep serialization is running.
-   *
-   * @return mixed
-   *   Depending on whether deep serialization is running or not the returned
-   *   value might be either the data value as returned by ::getValue() if deep
-   *   serialization is not running or additionally contain computed properties
-   *   next to the data values if deep serialization is running.
+   *   Whether a deep serialization should be performed.
+   *
+   * @return array[]
+   *   Depending on whether deep serialization is being performed or not the
+   *   returned value might be either the data value as returned by ::getValue()
+   *   if deep serialization is not being performed or additionally contain
+   *   computed properties next to the data values if deep serialization is
+   *   being performed.
    */
   public function getSerializationValue($deep_serialization);