diff --git a/junit-platform-engine/src/main/java/org/junit/platform/engine/TestEngine.java b/junit-platform-engine/src/main/java/org/junit/platform/engine/TestEngine.java
index 401fa19363c8..930b817e1b92 100644
--- a/junit-platform-engine/src/main/java/org/junit/platform/engine/TestEngine.java
+++ b/junit-platform-engine/src/main/java/org/junit/platform/engine/TestEngine.java
@@ -54,6 +54,8 @@ public interface TestEngine {
 	 * and JUnit Jupiter use {@code "junit-vintage"} and {@code "junit-jupiter"},
 	 * respectively. When in doubt, you may use the fully qualified name of your
 	 * custom {@code TestEngine} implementation class.
+	 *
+	 * @return the ID of this test engine; never {@code null} or blank
 	 */
 	String getId();