--- /dev/null
+<?php
+
+namespace Drupal\user\Plugin\Validation\Constraint;
+
+use Symfony\Component\Validator\Constraint;
+
+/**
+ * Checks if the plain text password is provided for editing a protected field.
+ *
+ * @Constraint(
+ * id = "ProtectedUserField",
+ * label = @Translation("Password required for protected field change", context = "Validation")
+ * )
+ */
+class ProtectedUserFieldConstraint extends Constraint {
+
+ /**
+ * Violation message.
+ *
+ * @var string
+ */
+ public $message = "Your current password is missing or incorrect; it's required to change the %name.";
+
+}