# UNDF: UNDF-2026-000000072
--- a/flink-runtime/src/main/java/org/apache/flink/runtime/jobgraph/JobGraph.java
+++ b/flink-runtime/src/main/java/org/apache/flink/runtime/jobgraph/JobGraph.java
@@ -117,8 +117,8 @@
-    /** Set of JAR files required to run this job. */
-    private final List<Path> userJars = new ArrayList<Path>();
+    /** Set of JAR files required to run this job (LinkedHashSet for O(1) dedup). */
+    private final LinkedHashSet<Path> userJars = new LinkedHashSet<>();

-    /** Set of blob keys identifying the JAR files required to run this job. */
-    private final List<PermanentBlobKey> userJarBlobKeys = new ArrayList<>();
+    /** Set of blob keys identifying the JAR files required to run this job (LinkedHashSet for O(1) dedup). */
+    private final LinkedHashSet<PermanentBlobKey> userJarBlobKeys = new LinkedHashSet<>();

@@ -563,9 +563,7 @@
     public void addJar(Path jar) {
         if (jar == null) {
             throw new IllegalArgumentException();
         }
-        if (!userJars.contains(jar)) {
-            userJars.add(jar);
-        }
+        userJars.add(jar);
     }

@@ -631,9 +629,7 @@
     public void addUserJarBlobKey(PermanentBlobKey key) {
         if (key == null) {
             throw new IllegalArgumentException();
         }
-        if (!userJarBlobKeys.contains(key)) {
-            userJarBlobKeys.add(key);
-        }
+        userJarBlobKeys.add(key);
     }

@@ -596,3 +594,3 @@
     public List<Path> getUserJars() {
-        return userJars;
+        return new ArrayList<>(userJars);
     }

@@ -656,3 +654,3 @@
     public List<PermanentBlobKey> getUserJarBlobKeys() {
-        return this.userJarBlobKeys;
+        return new ArrayList<>(userJarBlobKeys);
     }