diff --git a/gradle/documentation/render-javadoc.gradle b/gradle/documentation/render-javadoc.gradle
index 8e73fb1563ce..f76a2c401c23 100644
--- a/gradle/documentation/render-javadoc.gradle
+++ b/gradle/documentation/render-javadoc.gradle
@@ -423,7 +423,7 @@ class RenderJavadocTask extends DefaultTask {
       opts << [ '-linkoffline', url, dir ]
     }
 
-    opts << [ '--release', 17 ]
+    opts << [ '--release', 21 ]
     opts << '-Xdoclint:all,-missing'
 
     // Increase Javadoc's heap.