--- /dev/null
+<?php
+
+namespace Drupal\migrate\Audit;
+
+/**
+ * Defines an interface for destination and ID maps which track a highest ID.
+ *
+ * When implemented by destination plugins, getHighestId() should return the
+ * highest ID of the destination entity type that exists in the system. So, for
+ * example, the entity:node plugin should return the highest node ID that
+ * exists, regardless of whether it was created by a migration.
+ *
+ * When implemented by an ID map, getHighestId() should return the highest
+ * migrated ID of the destination entity type.
+ */
+interface HighestIdInterface {
+
+ /**
+ * Returns the highest ID tracked by the implementing plugin.
+ *
+ * @return int
+ * The highest ID.
+ */
+ public function getHighestId();
+
+}