--- /dev/null
+<?php
+
+namespace Drupal\migrate\Plugin\migrate\process;
+
+@trigger_error('The ' . __NAMESPACE__ . ' \DedupeEntityBase is deprecated in
+Drupal 8.4.x and will be removed before Drupal 9.0.0. Instead, use ' . __NAMESPACE__ . ' \MakeUniqueEntityFieldBase', E_USER_DEPRECATED);
+
+/**
+ * This abstract base contains the dedupe logic.
+ *
+ * These plugins avoid duplication at the destination. For example, when
+ * creating filter format names, the current value is checked against the
+ * existing filter format names and if it exists, a numeric postfix is added
+ * and incremented until a unique value is created.
+ *
+ * @link https://www.drupal.org/node/2345929 Online handbook documentation for dedupebase process plugin @endlink
+ *
+ * @deprecated in Drupal 8.4.x and will be removed in Drupal 9.0.x. Use
+ * \Drupal\migrate\Plugin\migrate\process\MakeUniqueBase instead.
+ */
+abstract class DedupeBase extends MakeUniqueBase {
+}