diff --git a/core/lib/Drupal/Core/Entity/Field/FieldItemBase.php b/core/lib/Drupal/Core/Entity/Field/FieldItemBase.php
index 62edc8d..b3c99ba 100644
--- a/core/lib/Drupal/Core/Entity/Field/FieldItemBase.php
+++ b/core/lib/Drupal/Core/Entity/Field/FieldItemBase.php
@@ -46,6 +46,15 @@
   protected $extraValues = array();
 
   /**
+   * Field definitions of the contained properties.
+   *
+   * @see self::getPropertyDefinitions()
+   *
+   * @var array
+   */
+  static $propertyDefinitions;
+
+  /**
    * Overrides ContextAwareTypedData::__construct().
    */
   public function __construct(array $definition, $name = NULL, ContextAwareInterface $parent = NULL) {
diff --git a/core/lib/Drupal/Core/Entity/Field/Type/BooleanItem.php b/core/lib/Drupal/Core/Entity/Field/Type/BooleanItem.php
index f73b013..cc935af 100644
--- a/core/lib/Drupal/Core/Entity/Field/Type/BooleanItem.php
+++ b/core/lib/Drupal/Core/Entity/Field/Type/BooleanItem.php
@@ -15,15 +15,6 @@
 class BooleanItem extends FieldItemBase {
 
   /**
-   * Definitions of the contained properties.
-   *
-   * @see BooleanItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements \Drupal\Core\TypedData\ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/lib/Drupal/Core/Entity/Field/Type/DateItem.php b/core/lib/Drupal/Core/Entity/Field/Type/DateItem.php
index 33b4ec4..1d73156 100644
--- a/core/lib/Drupal/Core/Entity/Field/Type/DateItem.php
+++ b/core/lib/Drupal/Core/Entity/Field/Type/DateItem.php
@@ -15,15 +15,6 @@
 class DateItem extends FieldItemBase {
 
   /**
-   * Definitions of the contained properties.
-   *
-   * @see DateItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements \Drupal\Core\TypedData\ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/lib/Drupal/Core/Entity/Field/Type/EntityReferenceItem.php b/core/lib/Drupal/Core/Entity/Field/Type/EntityReferenceItem.php
index 695a7ca..89cf6a7 100644
--- a/core/lib/Drupal/Core/Entity/Field/Type/EntityReferenceItem.php
+++ b/core/lib/Drupal/Core/Entity/Field/Type/EntityReferenceItem.php
@@ -18,15 +18,6 @@
 class EntityReferenceItem extends FieldItemBase {
 
   /**
-   * Definitions of the contained properties.
-   *
-   * @see EntityReferenceItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements \Drupal\Core\TypedData\ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/lib/Drupal/Core/Entity/Field/Type/IntegerItem.php b/core/lib/Drupal/Core/Entity/Field/Type/IntegerItem.php
index b58529e..5e2bbc9 100644
--- a/core/lib/Drupal/Core/Entity/Field/Type/IntegerItem.php
+++ b/core/lib/Drupal/Core/Entity/Field/Type/IntegerItem.php
@@ -15,15 +15,6 @@
 class IntegerItem extends FieldItemBase {
 
   /**
-   * Definitions of the contained properties.
-   *
-   * @see IntegerItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements \Drupal\Core\TypedData\ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/lib/Drupal/Core/Entity/Field/Type/LanguageItem.php b/core/lib/Drupal/Core/Entity/Field/Type/LanguageItem.php
index b3765b1..b97b825 100644
--- a/core/lib/Drupal/Core/Entity/Field/Type/LanguageItem.php
+++ b/core/lib/Drupal/Core/Entity/Field/Type/LanguageItem.php
@@ -16,15 +16,6 @@
 class LanguageItem extends FieldItemBase {
 
   /**
-   * Definitions of the contained properties.
-   *
-   * @see LanguageItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements \Drupal\Core\TypedData\ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/lib/Drupal/Core/Entity/Field/Type/StringItem.php b/core/lib/Drupal/Core/Entity/Field/Type/StringItem.php
index 7a6fdc0..9870ccd 100644
--- a/core/lib/Drupal/Core/Entity/Field/Type/StringItem.php
+++ b/core/lib/Drupal/Core/Entity/Field/Type/StringItem.php
@@ -15,15 +15,6 @@
 class StringItem extends FieldItemBase {
 
   /**
-   * Definitions of the contained properties.
-   *
-   * @see StringItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements \Drupal\Core\TypedData\ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/lib/Drupal/Core/Entity/Field/Type/UriItem.php b/core/lib/Drupal/Core/Entity/Field/Type/UriItem.php
index e5b84d4..645a2d6 100644
--- a/core/lib/Drupal/Core/Entity/Field/Type/UriItem.php
+++ b/core/lib/Drupal/Core/Entity/Field/Type/UriItem.php
@@ -15,15 +15,6 @@
 class UriItem extends FieldItemBase {
 
   /**
-   * Field definitions of the contained properties.
-   *
-   * @see self::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/datetime/lib/Drupal/datetime/Type/DateTimeItem.php b/core/modules/datetime/lib/Drupal/datetime/Type/DateTimeItem.php
index 2d14e5a..643054a 100644
--- a/core/modules/datetime/lib/Drupal/datetime/Type/DateTimeItem.php
+++ b/core/modules/datetime/lib/Drupal/datetime/Type/DateTimeItem.php
@@ -15,15 +15,6 @@
 class DateTimeItem extends FieldItemBase {
 
   /**
-   * Field definitions of the contained properties.
-   *
-   * @see self::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/email/lib/Drupal/email/Type/EmailItem.php b/core/modules/email/lib/Drupal/email/Type/EmailItem.php
index c1705f5..dc53003 100644
--- a/core/modules/email/lib/Drupal/email/Type/EmailItem.php
+++ b/core/modules/email/lib/Drupal/email/Type/EmailItem.php
@@ -15,15 +15,6 @@
 class EmailItem extends FieldItemBase {
 
   /**
-   * Definitions of the contained properties.
-   *
-   * @see EmailItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/entity_reference/lib/Drupal/entity_reference/Type/ConfigurableEntityReferenceItem.php b/core/modules/entity_reference/lib/Drupal/entity_reference/Type/ConfigurableEntityReferenceItem.php
index eea88c7..5e2f92e 100644
--- a/core/modules/entity_reference/lib/Drupal/entity_reference/Type/ConfigurableEntityReferenceItem.php
+++ b/core/modules/entity_reference/lib/Drupal/entity_reference/Type/ConfigurableEntityReferenceItem.php
@@ -21,15 +21,6 @@
 class ConfigurableEntityReferenceItem extends EntityReferenceItem {
 
   /**
-   * Definitions of the contained properties.
-   *
-   * @see ConfigurableEntityReferenceItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Overrides \Drupal\Core\Entity\Field\Type\EntityReferenceItem::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Type/ShapeItem.php b/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Type/ShapeItem.php
index 1a67329..28fd4ce 100644
--- a/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Type/ShapeItem.php
+++ b/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Type/ShapeItem.php
@@ -15,15 +15,6 @@
 class ShapeItem extends FieldItemBase {
 
   /**
-   * Property definitions of the contained properties.
-   *
-   * @see ShapeItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements \Drupal\Core\TypedData\ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Type/TestItem.php b/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Type/TestItem.php
index 0c61d15..977fff1 100644
--- a/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Type/TestItem.php
+++ b/core/modules/field/tests/modules/field_test/lib/Drupal/field_test/Type/TestItem.php
@@ -15,15 +15,6 @@
 class TestItem extends FieldItemBase {
 
   /**
-   * Property definitions of the contained properties.
-   *
-   * @see TestItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements \Drupal\Core\TypedData\ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/file/lib/Drupal/file/Type/FileItem.php b/core/modules/file/lib/Drupal/file/Type/FileItem.php
index cecce05..f9c04bf 100644
--- a/core/modules/file/lib/Drupal/file/Type/FileItem.php
+++ b/core/modules/file/lib/Drupal/file/Type/FileItem.php
@@ -15,15 +15,6 @@
 class FileItem extends FieldItemBase {
 
   /**
-   * Property definitions of the contained properties.
-   *
-   * @see FileItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements \Drupal\Core\TypedData\ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/image/lib/Drupal/image/Type/ImageItem.php b/core/modules/image/lib/Drupal/image/Type/ImageItem.php
index 72bf09c..45422a4 100644
--- a/core/modules/image/lib/Drupal/image/Type/ImageItem.php
+++ b/core/modules/image/lib/Drupal/image/Type/ImageItem.php
@@ -15,15 +15,6 @@
 class ImageItem extends FieldItemBase {
 
   /**
-   * Property definitions of the contained properties.
-   *
-   * @see ImageItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements \Drupal\Core\TypedData\ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/link/lib/Drupal/link/Type/LinkItem.php b/core/modules/link/lib/Drupal/link/Type/LinkItem.php
index ad20400..a955319 100644
--- a/core/modules/link/lib/Drupal/link/Type/LinkItem.php
+++ b/core/modules/link/lib/Drupal/link/Type/LinkItem.php
@@ -15,15 +15,6 @@
 class LinkItem extends FieldItemBase {
 
   /**
-   * Property definitions of the contained properties.
-   *
-   * @see self::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/number/lib/Drupal/number/Type/DecimalItem.php b/core/modules/number/lib/Drupal/number/Type/DecimalItem.php
index 5235f21..af653b3 100644
--- a/core/modules/number/lib/Drupal/number/Type/DecimalItem.php
+++ b/core/modules/number/lib/Drupal/number/Type/DecimalItem.php
@@ -15,15 +15,6 @@
 class DecimalItem extends FieldItemBase {
 
   /**
-   * Definitions of the contained properties.
-   *
-   * @see DecimalItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/number/lib/Drupal/number/Type/FloatItem.php b/core/modules/number/lib/Drupal/number/Type/FloatItem.php
index 8f8fddd..9d3e9e2 100644
--- a/core/modules/number/lib/Drupal/number/Type/FloatItem.php
+++ b/core/modules/number/lib/Drupal/number/Type/FloatItem.php
@@ -15,15 +15,6 @@
 class FloatItem extends FieldItemBase {
 
   /**
-   * Definitions of the contained properties.
-   *
-   * @see FloatItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/number/lib/Drupal/number/Type/IntegerItem.php b/core/modules/number/lib/Drupal/number/Type/IntegerItem.php
index 6b126f1..c0e1259 100644
--- a/core/modules/number/lib/Drupal/number/Type/IntegerItem.php
+++ b/core/modules/number/lib/Drupal/number/Type/IntegerItem.php
@@ -15,15 +15,6 @@
 class IntegerItem extends FieldItemBase {
 
   /**
-   * Definitions of the contained properties.
-   *
-   * @see IntegerItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/taxonomy/lib/Drupal/taxonomy/Type/TaxonomyTermReferenceItem.php b/core/modules/taxonomy/lib/Drupal/taxonomy/Type/TaxonomyTermReferenceItem.php
index 7f7ab02..db61dea 100644
--- a/core/modules/taxonomy/lib/Drupal/taxonomy/Type/TaxonomyTermReferenceItem.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/Type/TaxonomyTermReferenceItem.php
@@ -15,15 +15,6 @@
 class TaxonomyTermReferenceItem extends FieldItemBase {
 
   /**
-   * Property definitions of the contained properties.
-   *
-   * @see TaxonomyTermReferenceItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements \Drupal\Core\TypedData\ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/telephone/lib/Drupal/telephone/Type/TelephoneItem.php b/core/modules/telephone/lib/Drupal/telephone/Type/TelephoneItem.php
index 195e4a5..97fd2b3 100644
--- a/core/modules/telephone/lib/Drupal/telephone/Type/TelephoneItem.php
+++ b/core/modules/telephone/lib/Drupal/telephone/Type/TelephoneItem.php
@@ -15,15 +15,6 @@
 class TelephoneItem extends FieldItemBase {
 
   /**
-   * Definitions of the contained properties.
-   *
-   * @see TelephoneItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
diff --git a/core/modules/text/lib/Drupal/text/Type/TextItem.php b/core/modules/text/lib/Drupal/text/Type/TextItem.php
index d7aefc7..09f7d35 100644
--- a/core/modules/text/lib/Drupal/text/Type/TextItem.php
+++ b/core/modules/text/lib/Drupal/text/Type/TextItem.php
@@ -15,15 +15,6 @@
 class TextItem extends FieldItemBase {
 
   /**
-   * Definitions of the contained properties.
-   *
-   * @see TextItem::getPropertyDefinitions()
-   *
-   * @var array
-   */
-  static $propertyDefinitions;
-
-  /**
    * Implements ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {