--- /dev/null
+<?php
+
+namespace Drupal\field_test\Plugin\Validation\Constraint;
+
+use Symfony\Component\Validator\Constraints\NotEqualTo;
+
+/**
+ * Checks if a value is not equal.
+ *
+ * @Constraint(
+ * id = "TestField",
+ * label = @Translation("Test Field", context = "Validation"),
+ * type = { "integer" }
+ * )
+ */
+class TestFieldConstraint extends NotEqualTo {
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getRequiredOptions() {
+ return ['value'];
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function validatedBy() {
+ return '\Symfony\Component\Validator\Constraints\NotEqualToValidator';
+ }
+
+}