diff --git a/src/Form/ConditionalFieldForm.php b/src/Form/ConditionalFieldForm.php
index 6c8a651..2232e3a 100644
--- a/src/Form/ConditionalFieldForm.php
+++ b/src/Form/ConditionalFieldForm.php
@@ -178,7 +178,20 @@ class ConditionalFieldForm extends FormBase {
     parent::validateForm($form, $form_state);
   }
 
-  protected function requiredFieldIsNotVisible(FieldDefinitionInterface $field, ?string $state): bool {
+  /**
+   * Determine if a field is configured to be required, but not visible.
+   *
+   * This is considered an error condition as a user would not be able to fill
+   * out the field.
+   *
+   * @param \Drupal\Core\Field\FieldDefinitionInterface $field
+   *   The field to evaluate.
+   * @param null|string $state
+   *   The configured state for the field.
+   *
+   * @return bool
+   *   TRUE if the field is required but not visible; FALSE otherwise.
+   */  protected function requiredFieldIsNotVisible(FieldDefinitionInterface $field, $state): bool {
     return method_exists($field, 'isRequired') &&
       $field->isRequired() &&
       in_array($state, ['!visible', 'disabled', '!required']);