From 2a279dfc59fa1f8cb91813024536b80d2df18a7e Mon Sep 17 00:00:00 2001
From: jean-philippe bempel <jean-philippe.bempel@datadoghq.com>
Date: Thu, 8 Jan 2026 16:39:03 +0100
Subject: [PATCH] fix NullPointerException in ClassesToRetransformFinder

add check against null from classes returned by
Instrumentation::getAllLoadedClasses
---
 .../datadog/debugger/agent/ClassesToRetransformFinder.java   | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/agent/ClassesToRetransformFinder.java b/dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/agent/ClassesToRetransformFinder.java
index 31a85c76fc6..d91a159a914 100644
--- a/dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/agent/ClassesToRetransformFinder.java
+++ b/dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/agent/ClassesToRetransformFinder.java
@@ -43,6 +43,11 @@ public List<Class<?>> getAllLoadedChangedClasses(
     List<Class<?>> classesToBeTransformed = new ArrayList<>();
     Trie changedClasses = getAllChangedClasses(comparer);
     for (Class<?> clazz : allLoadedClasses) {
+      if (clazz == null) {
+        // clazz could be null in the array returned by Instrumentation::getAllLoadedClasses
+        // probably because class unloading
+        continue;
+      }
       if (lookupClass(changedClasses, clazz)) {
         classesToBeTransformed.add(clazz);
       }