diff --git a/core/lib/Drupal/Core/Entity/ContentEntityType.php b/core/lib/Drupal/Core/Entity/ContentEntityType.php
index c4033b5..0e26c3b 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityType.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityType.php
@@ -17,11 +17,6 @@ class ContentEntityType extends EntityType implements ContentEntityTypeInterface
   /**
    * {@inheritdoc}
    */
-  protected $supports_validation = TRUE;
-
-  /**
-   * {@inheritdoc}
-   */
   public function __construct($definition) {
     parent::__construct($definition);
     $this->handlers += [
diff --git a/core/lib/Drupal/Core/Entity/EntityType.php b/core/lib/Drupal/Core/Entity/EntityType.php
index 1132a7a..5f6589a 100644
--- a/core/lib/Drupal/Core/Entity/EntityType.php
+++ b/core/lib/Drupal/Core/Entity/EntityType.php
@@ -278,13 +278,6 @@ class EntityType extends PluginDefinition implements EntityTypeInterface {
   protected $additional = [];
 
   /**
-   * Entity type supports validation.
-   *
-   * @var bool
-   */
-  protected $supports_validation = FALSE;
-
-  /**
    * Constructs a new EntityType.
    *
    * @param array $definition
diff --git a/core/lib/Drupal/Core/Entity/FieldableEntityInterface.php b/core/lib/Drupal/Core/Entity/FieldableEntityInterface.php
index d21a2a8..4fa05b6 100644
--- a/core/lib/Drupal/Core/Entity/FieldableEntityInterface.php
+++ b/core/lib/Drupal/Core/Entity/FieldableEntityInterface.php
@@ -20,7 +20,7 @@
  *
  * @ingroup entity_api
  */
-interface FieldableEntityInterface extends EntityInterface {
+interface FieldableEntityInterface extends EntityInterface, ValidatableInterface {
 
   /**
    * Provides base field definitions for an entity type.
@@ -209,31 +209,4 @@ public function getTranslatableFields($include_computed = TRUE);
    */
   public function onChange($field_name);
 
-  /**
-   * Validates the currently set values.
-   *
-   * @return \Drupal\Core\Entity\EntityConstraintViolationListInterface
-   *   A list of constraint violations. If the list is empty, validation
-   *   succeeded.
-   */
-  public function validate();
-
-  /**
-   * Checks whether entity validation is required before saving the entity.
-   *
-   * @return bool
-   *   TRUE if validation is required, FALSE if not.
-   */
-  public function isValidationRequired();
-
-  /**
-   * Sets whether entity validation is required before saving the entity.
-   *
-   * @param bool $required
-   *   TRUE if validation is required, FALSE otherwise.
-   *
-   * @return $this
-   */
-  public function setValidationRequired($required);
-
 }
diff --git a/core/lib/Drupal/Core/Entity/ValidatableInterface.php b/core/lib/Drupal/Core/Entity/ValidatableInterface.php
new file mode 100644
index 0000000..3fded8b
--- /dev/null
+++ b/core/lib/Drupal/Core/Entity/ValidatableInterface.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace Drupal\Core\Entity;
+
+/**
+ * Interface for entities that support validation.
+ *
+ * @ingroup entity_api
+ */
+interface ValidatableInterface {
+
+  /**
+   * Validates the currently set values.
+   *
+   * @return \Drupal\Core\Entity\EntityConstraintViolationListInterface
+   *   A list of constraint violations. If the list is empty, validation
+   *   succeeded.
+   */
+  public function validate();
+
+  /**
+   * Checks whether entity validation is required before saving the entity.
+   *
+   * @return bool
+   *   TRUE if validation is required, FALSE if not.
+   */
+  public function isValidationRequired();
+
+  /**
+   * Sets whether entity validation is required before saving the entity.
+   *
+   * @param bool $required
+   *   TRUE if validation is required, FALSE otherwise.
+   *
+   * @return $this
+   */
+  public function setValidationRequired($required);
+
+}
diff --git a/core/modules/config/tests/config_test/src/ConfigTestInterface.php b/core/modules/config/tests/config_test/src/ConfigTestInterface.php
index e2cf7f4..3a8c29f 100644
--- a/core/modules/config/tests/config_test/src/ConfigTestInterface.php
+++ b/core/modules/config/tests/config_test/src/ConfigTestInterface.php
@@ -3,10 +3,11 @@
 namespace Drupal\config_test;
 
 use Drupal\Core\Config\Entity\ConfigEntityInterface;
+use Drupal\Core\Entity\ValidatableInterface;
 
 /**
  * Provides an interface defining a config_test entity.
  */
-interface ConfigTestInterface extends ConfigEntityInterface {
+interface ConfigTestInterface extends ConfigEntityInterface, ValidatableInterface {
 
 }
diff --git a/core/modules/config/tests/config_test/src/Entity/ConfigTest.php b/core/modules/config/tests/config_test/src/Entity/ConfigTest.php
index 4f84ecf..1bd1d8d 100644
--- a/core/modules/config/tests/config_test/src/Entity/ConfigTest.php
+++ b/core/modules/config/tests/config_test/src/Entity/ConfigTest.php
@@ -22,7 +22,6 @@
  *     },
  *     "access" = "Drupal\config_test\ConfigTestAccessControlHandler"
  *   },
- *   supports_validation = TRUE,
  *   config_prefix = "dynamic",
  *   entity_keys = {
  *     "id" = "id",
diff --git a/core/modules/content_moderation/src/Entity/ContentModerationState.php b/core/modules/content_moderation/src/Entity/ContentModerationState.php
index f2d74b8..e54fbbe 100644
--- a/core/modules/content_moderation/src/Entity/ContentModerationState.php
+++ b/core/modules/content_moderation/src/Entity/ContentModerationState.php
@@ -31,7 +31,6 @@
  *   data_table = "content_moderation_state_field_data",
  *   revision_data_table = "content_moderation_state_field_revision",
  *   translatable = TRUE,
- *   supports_validation = FALSE,
  *   entity_keys = {
  *     "id" = "id",
  *     "revision" = "revision_id",
diff --git a/core/modules/rest/src/Plugin/rest/resource/EntityResource.php b/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
index 3b0a8ad..85bef2d 100644
--- a/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
+++ b/core/modules/rest/src/Plugin/rest/resource/EntityResource.php
@@ -12,6 +12,7 @@
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\EntityStorageException;
+use Drupal\Core\Entity\ValidatableInterface;
 use Drupal\rest\Plugin\ResourceBase;
 use Drupal\rest\ResourceResponse;
 use Psr\Log\LoggerInterface;
@@ -355,7 +356,7 @@ protected function getBaseRoute($canonical_path, $method) {
   public function availableMethods() {
     $methods = parent::availableMethods();
     // Without validation, it's impossible to support creation or modification.
-    if (!$this->entityType->get('supports_validation')) {
+    if (!$this->entityType->entityClassImplements(ValidatableInterface::class)) {
       $unsupported_methods = ['POST', 'PUT', 'DELETE', 'PATCH'];
       $methods = array_diff($methods, $unsupported_methods);
     }
diff --git a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
index f08f780..68b00df 100644
--- a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
@@ -9,6 +9,7 @@
 use Drupal\Core\Config\Entity\ConfigEntityInterface;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\FieldableEntityInterface;
+use Drupal\Core\Entity\ValidatableInterface;
 use Drupal\Core\Field\Plugin\Field\FieldType\BooleanItem;
 use Drupal\Core\Field\Plugin\Field\FieldType\EntityReferenceItem;
 use Drupal\Core\Url;
@@ -694,7 +695,7 @@ protected static function recursiveKSort(array &$array) {
    * Tests a POST request for an entity, plus edge cases to ensure good DX.
    */
   public function testPost() {
-    if (!$this->entity->getEntityType()->get('supports_validation')) {
+    if (!$this->entity->getEntityType()->entityClassImplements(ValidatableInterface::class)) {
       $this->assertTrue(TRUE, "This entity type doesn't support POSTing.");
       return;
     }
@@ -935,7 +936,7 @@ public function testPost() {
    * Tests a PATCH request for an entity, plus edge cases to ensure good DX.
    */
   public function testPatch() {
-    if (!$this->entity->getEntityType()->get('supports_validation')) {
+    if (!$this->entity->getEntityType()->entityClassImplements(ValidatableInterface::class)) {
       $this->assertTrue(TRUE, "This entity type doesn't support PATCHing.");
       return;
     }
@@ -1165,7 +1166,7 @@ public function testPatch() {
    * Tests a DELETE request for an entity, plus edge cases to ensure good DX.
    */
   public function testDelete() {
-    if (!$this->entity->getEntityType()->get('supports_validation')) {
+    if (!$this->entity->getEntityType()->entityClassImplements(ValidatableInterface::class)) {
       $this->assertTrue(TRUE, "This entity type doesn't support DELETEing.");
       return;
     }