diff --git a/core/modules/datetime/src/Plugin/Field/FieldType/DateRangeItem.php b/core/modules/datetime/src/Plugin/Field/FieldType/DateRangeItem.php
index dfe036f..49d6f49 100644
--- a/core/modules/datetime/src/Plugin/Field/FieldType/DateRangeItem.php
+++ b/core/modules/datetime/src/Plugin/Field/FieldType/DateRangeItem.php
@@ -7,6 +7,7 @@
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\TypedData\DataDefinition;
 use Drupal\Core\Field\FieldItemBase;
+use Drupal\datetime\DateTimeComputed;
 
 /**
  * Plugin implementation of the 'daterange' field type.
@@ -58,7 +59,7 @@ public static function propertyDefinitions(FieldStorageDefinitionInterface $fiel
       ->setLabel(t('Computed start date'))
       ->setDescription(t('The computed start DateTime object.'))
       ->setComputed(TRUE)
-      ->setClass('\Drupal\datetime\DateTimeComputed')
+      ->setClass(DateTimeComputed::class)
       ->setSetting('date source', 'value');
 
     $properties['value2'] = DataDefinition::create('datetime_iso8601')
@@ -69,7 +70,7 @@ public static function propertyDefinitions(FieldStorageDefinitionInterface $fiel
       ->setLabel(t('Computed end date'))
       ->setDescription(t('The computed end DateTime object.'))
       ->setComputed(TRUE)
-      ->setClass('\Drupal\datetime\DateTimeComputed')
+      ->setClass(DateTimeComputed::class)
       ->setSetting('date source', 'value2');
 
     return $properties;
@@ -169,12 +170,4 @@ public function onChange($property_name, $notify = TRUE) {
     parent::onChange($property_name, $notify);
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public static function mainPropertyName() {
-    // A date range item is a compound value, so there is no main property name.
-    return NULL;
-  }
-
 }
diff --git a/core/modules/datetime/src/Tests/DateRangeFieldTest.php b/core/modules/datetime/src/Tests/DateRangeFieldTest.php
index 512840a..c005668 100644
--- a/core/modules/datetime/src/Tests/DateRangeFieldTest.php
+++ b/core/modules/datetime/src/Tests/DateRangeFieldTest.php
@@ -132,7 +132,7 @@ protected function setUp() {
   /**
    * Tests date field functionality.
    */
-  function testDateRangeField() {
+  public function testDateRangeField() {
     $field_name = $this->fieldStorage->getName();
 
     // Loop through defined timezones to test that date-only fields work at the
@@ -253,7 +253,7 @@ function testDateRangeField() {
   /**
    * Tests date and time field.
    */
-  function testDatetimeRangeField() {
+  public function testDatetimeRangeField() {
     $field_name = $this->fieldStorage->getName();
 
     // Ensure the field to a datetime field.
@@ -349,7 +349,7 @@ function testDatetimeRangeField() {
   /**
    * Tests all-day field.
    */
-  function testAlldayRangeField() {
+  public function testAlldayRangeField() {
     $field_name = $this->fieldStorage->getName();
 
     // Ensure field is set to a all-day field.
@@ -440,7 +440,7 @@ function testAlldayRangeField() {
   /**
    * Tests Date Range List Widget functionality.
    */
-  function testDatelistWidget() {
+  public function testDatelistWidget() {
     $field_name = $this->fieldStorage->getName();
 
     // Ensure field is set to a date only field.
@@ -770,7 +770,7 @@ protected function datelistDataProvider() {
   /**
    * Test default value functionality.
    */
-  function testDefaultValue() {
+  public function testDefaultValue() {
     // Create a test content type.
     $this->drupalCreateContentType(['type' => 'date_content']);
 
@@ -905,7 +905,7 @@ function testDefaultValue() {
   /**
    * Test that invalid values are caught and marked as invalid.
    */
-  function testInvalidField() {
+  public function testInvalidField() {
     // Change the field to a datetime field.
     $this->fieldStorage->setSetting('daterange_type', DateRangeItem::DATERANGE_TYPE_DATETIME);
     $this->fieldStorage->save();