--- /dev/null
+<?php
+
+namespace Drupal\content_translation\Plugin\Validation\Constraint;
+
+use Symfony\Component\Validator\Constraint;
+
+/**
+ * Validation constraint for the entity changed timestamp.
+ *
+ * @internal
+ *
+ * @Constraint(
+ * id = "ContentTranslationSynchronizedFields",
+ * label = @Translation("Content translation synchronized fields", context = "Validation"),
+ * type = {"entity"}
+ * )
+ */
+class ContentTranslationSynchronizedFieldsConstraint extends Constraint {
+
+ // In this case "elements" refers to "field properties", in fact it is what we
+ // are using in the UI elsewhere.
+ public $defaultRevisionMessage = 'Non-translatable field elements can only be changed when updating the current revision.';
+ public $defaultTranslationMessage = 'Non-translatable field elements can only be changed when updating the original language.';
+
+}