diff -u b/core/modules/inline_form_errors/inline_form_errors.module b/core/modules/inline_form_errors/inline_form_errors.module
--- b/core/modules/inline_form_errors/inline_form_errors.module
+++ b/core/modules/inline_form_errors/inline_form_errors.module
@@ -6,7 +6,6 @@
  */
 
 use Drupal\Core\Form\FormStateInterface;
-use Drupal\Core\Render\Element\FormElementInterface;
 use Drupal\Core\Routing\RouteMatchInterface;
 
 /**
@@ -55,9 +54,9 @@
  */
 function inline_form_errors_element_info_alter(array &$info) {
   // Add a processor for form elements and pseudo form elements.
-  $determiner = \Drupal::service('inline_form_errors.form_element_determiner');
+  $supported_render_element_helper = \Drupal::service('inline_form_errors.supported_render_element_helper');
   foreach ($info as $element_type => $element_info) {
-    if ($determiner->isFormElement($element_type)) {
+    if ($supported_render_element_helper->supportsInlineFormErrors($element_type)) {
       $info[$element_type]['#process'][] = 'inline_form_errors_process_form_element';
     }
   }
diff -u b/core/modules/inline_form_errors/inline_form_errors.services.yml b/core/modules/inline_form_errors/inline_form_errors.services.yml
--- b/core/modules/inline_form_errors/inline_form_errors.services.yml
+++ b/core/modules/inline_form_errors/inline_form_errors.services.yml
@@ -1,4 +1,4 @@
 services:
-  inline_form_errors.form_element_determiner:
-    class: Drupal\inline_form_errors\FormElementDeterminer
+  inline_form_errors.supported_render_element_helper:
+    class: Drupal\inline_form_errors\SupportedRenderElementHelper
     arguments: ['@plugin.manager.element_info']
reverted:
--- b/core/modules/inline_form_errors/src/FormElementDeterminer.php
+++ /dev/null
@@ -1,78 +0,0 @@
-<?php
-
-namespace Drupal\inline_form_errors;
-
-use Drupal\Core\Render\Element\FormElementInterface;
-use Drupal\Core\Render\ElementInfoManager;
-
-/**
- * Provides a way to determine if a render array is for a form element.
- */
-class FormElementDeterminer {
-
-  /**
-   * A list of pseudo form elements.
-   *
-   * Define a list of elements that are not form elements but are primarily
-   * used in forms and supported by Inline Form Errors.
-   *
-   * @var array
-   */
-  protected $pseudoFormElements = [
-    'details',
-    'fieldset',
-    'datetime_wrapper',
-  ];
-
-  /**
-   * The element info manager.
-   *
-   * @var \Drupal\Core\Render\ElementInfoManager
-   */
-  protected $elementInfoManager;
-
-  /**
-   * FormElementDeterminer constructor.
-   *
-   * @param \Drupal\Core\Render\ElementInfoManager $element_info_manager
-   *   The element info manager.
-   */
-  public function __construct(ElementInfoManager $element_info_manager) {
-    $this->elementInfoManager = $element_info_manager;
-  }
-
-  /**
-   * Determine if a render element type also is a form element.
-   *
-   * @param string $element_type
-   *   The element type.
-   *
-   * @return bool
-   *   TRUE if the given element type is a form element or FALSE otherwise.
-   */
-  public function isFormElement($element_type) {
-    return in_array($element_type, $this->pseudoFormElements) || $this->elementInstanceOfFormElementInterface($element_type);
-  }
-
-  /**
-   * Determine if a render element type implements FormElementInterface.
-   *
-   * @param string $element_type
-   *   The element type.
-   *
-   * @return bool
-   *   TRUE if the given element type implements FormElementInterface or FALSE
-   *   otherwise.
-   */
-  protected function elementInstanceOfFormElementInterface($element_type) {
-    $element_definitions = $this->elementInfoManager->getDefinitions();
-
-    if (!empty($element_definitions[$element_type])) {
-      $interfaces = class_implements($element_definitions[$element_type]['class']);
-      return isset($interfaces['Drupal\Core\Render\Element\FormElementInterface']);
-    }
-
-    return FALSE;
-  }
-
-}
reverted:
--- b/core/modules/inline_form_errors/tests/src/Unit/FormElementDeterminerTest.php
+++ /dev/null
@@ -1,58 +0,0 @@
-<?php
-
-namespace Drupal\Tests\inline_form_errors\Unit;
-
-use Drupal\Core\Cache\CacheBackendInterface;
-use Drupal\Core\Cache\CacheTagsInvalidatorInterface;
-use Drupal\Core\Extension\ModuleHandlerInterface;
-use Drupal\Core\Render\Element\ElementInterface;
-use Drupal\Core\Render\Element\FormElementInterface;
-use Drupal\Core\Render\ElementInfoManager;
-use Drupal\Core\Theme\ThemeManagerInterface;
-use Drupal\inline_form_errors\FormElementDeterminer;
-use Drupal\Tests\UnitTestCase;
-
-/**
- * @coversDefaultClass \Drupal\inline_form_errors\FormElementDeterminer
- * @group InlineFormErrors
- */
-class FormElementDeterminerTest extends UnitTestCase {
-
-  /**
-   * @covers ::isFormElement
-   * @covers ::elementInstanceOfFormElementInterface
-   */
-  public function testIsFormElement() {
-    $element_info_manager = $this->getMockBuilder(ElementInfoManager::class)
-      ->setConstructorArgs([
-        $this->getMock(\Traversable::class),
-        $this->getMock(CacheBackendInterface::class),
-        $this->getMock(CacheTagsInvalidatorInterface::class),
-        $this->getMock(ModuleHandlerInterface::class),
-        $this->getMock(ThemeManagerInterface::class),
-      ])
-      ->setMethods(['getDefinitions', 'createInstance'])
-      ->getMock();
-
-    $element_info_manager->expects($this->any())
-      ->method('getDefinitions')
-      ->willReturn([
-        'form_element_type' => ['class' => '\Drupal\Core\Render\Element\FormElement'],
-        'element_type' => ['class' => '\Drupal\Core\Render\Element\RenderElement'],
-      ]);
-
-    $form_element_determiner = new FormElementDeterminer($element_info_manager);
-
-    // Test that an element implementing FormElementInterface is detected.
-    $this->assertTrue($form_element_determiner->isFormElement('form_element_type'));
-
-    // Test that an element implementing only ElementInterface returns FALSE.
-    $this->assertFalse($form_element_determiner->isFormElement('element_type'));
-
-    // Test that any element marked as supported by inline form errors is
-    // detected. The 'details' element is one of the types specified in
-    // \Drupal\inline_form_errors\FormElementDeterminer::$pseudoFormElements.
-    $this->assertTrue($form_element_determiner->isFormElement('details'));
-  }
-
-}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/inline_form_errors/src/SupportedRenderElementHelper.php
@@ -0,0 +1,79 @@
+<?php
+
+namespace Drupal\inline_form_errors;
+
+use Drupal\Core\Render\ElementInfoManager;
+
+/**
+ * Provides a way to determine if a render element type supports inline form
+ * errors.
+ */
+class SupportedRenderElementHelper {
+
+  /**
+   * A list of pseudo form elements.
+   *
+   * Define a list of elements that are not form elements but are primarily
+   * used in forms and supported by Inline Form Errors.
+   *
+   * @var array
+   */
+  protected $pseudoFormElements = [
+    'details',
+    'fieldset',
+    'datetime_wrapper',
+  ];
+
+  /**
+   * The element info manager.
+   *
+   * @var \Drupal\Core\Render\ElementInfoManager
+   */
+  protected $elementInfoManager;
+
+  /**
+   * SupportedRenderElementHelper constructor.
+   *
+   * @param \Drupal\Core\Render\ElementInfoManager $element_info_manager
+   *   The element info manager.
+   */
+  public function __construct(ElementInfoManager $element_info_manager) {
+    $this->elementInfoManager = $element_info_manager;
+  }
+
+  /**
+   * Determine if a render element type supports inline form errors.
+   *
+   * @param string $element_type
+   *   The element type.
+   *
+   * @return bool
+   *   TRUE if the given element type is a form element or a render element
+   *   which supports inline form errors, or FALSE otherwise.
+   */
+  public function supportsInlineFormErrors($element_type) {
+    return in_array($element_type, $this->pseudoFormElements) || $this->elementInstanceOfFormElementInterface($element_type);
+  }
+
+  /**
+   * Determine if a render element type implements FormElementInterface.
+   *
+   * @param string $element_type
+   *   The element type.
+   *
+   * @return bool
+   *   TRUE if the given element type implements FormElementInterface or FALSE
+   *   otherwise.
+   */
+  protected function elementInstanceOfFormElementInterface($element_type) {
+    $element_definitions = $this->elementInfoManager->getDefinitions();
+
+    if (!empty($element_definitions[$element_type])) {
+      $interfaces = class_implements($element_definitions[$element_type]['class']);
+      return isset($interfaces['Drupal\Core\Render\Element\FormElementInterface']);
+    }
+
+    return FALSE;
+  }
+
+}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/inline_form_errors/tests/src/Unit/SupportedRenderElementHelperTest.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace Drupal\Tests\inline_form_errors\Unit;
+
+use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\Cache\CacheTagsInvalidatorInterface;
+use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Render\ElementInfoManager;
+use Drupal\Core\Theme\ThemeManagerInterface;
+use Drupal\inline_form_errors\SupportedRenderElementHelper;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * @coversDefaultClass \Drupal\inline_form_errors\SupportedRenderElementHelper
+ * @group InlineFormErrors
+ */
+class SupportedRenderElementHelperTest extends UnitTestCase {
+
+  /**
+   * @covers ::supportsInlineFormErrors
+   * @covers ::elementInstanceOfFormElementInterface
+   */
+  public function testSupportsInlineFormErrors() {
+    $element_info_manager = $this->getMockBuilder(ElementInfoManager::class)
+      ->setConstructorArgs([
+        $this->getMock(\Traversable::class),
+        $this->getMock(CacheBackendInterface::class),
+        $this->getMock(CacheTagsInvalidatorInterface::class),
+        $this->getMock(ModuleHandlerInterface::class),
+        $this->getMock(ThemeManagerInterface::class),
+      ])
+      ->setMethods(['getDefinitions', 'createInstance'])
+      ->getMock();
+
+    $element_info_manager->expects($this->any())
+      ->method('getDefinitions')
+      ->willReturn([
+        'form_element_type' => ['class' => '\Drupal\Core\Render\Element\FormElement'],
+        'render_element_type' => ['class' => '\Drupal\Core\Render\Element\RenderElement'],
+      ]);
+
+    $supported_render_element_helper = new SupportedRenderElementHelper($element_info_manager);
+
+    // Test that an element implementing FormElementInterface is detected.
+    $this->assertTrue($supported_render_element_helper->supportsInlineFormErrors('form_element_type'));
+
+    // Test that an element implementing only ElementInterface returns FALSE.
+    $this->assertFalse($supported_render_element_helper->supportsInlineFormErrors('render_element_type'));
+
+    // Test that any element marked as supported by inline form errors is
+    // detected. The 'details' element is one of the types specified in
+    // \Drupal\inline_form_errors\SupportedRenderElementHelper::$pseudoFormElements.
+    $this->assertTrue($supported_render_element_helper->supportsInlineFormErrors('details'));
+  }
+
+}