From c985b00fa42e269b4083750e926ea015ba22ae92 Mon Sep 17 00:00:00 2001
From: Andreas <andreas.mueller@openconcept.com>
Date: Thu, 1 Jan 2026 16:18:59 +0100
Subject: [PATCH] SONARJAVA java:S6204 should not raise an issue when
 addFirst/addLast/removeFirst/removeLast is called on the list

---
 .../checks/CollectorsToListCheckSample.java   | 20 +++++++++++++++++++
 .../java/checks/CollectorsToListCheck.java    |  3 ++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/java-checks-test-sources/default/src/main/java/checks/CollectorsToListCheckSample.java b/java-checks-test-sources/default/src/main/java/checks/CollectorsToListCheckSample.java
index 7f017ef33c4..f6e4636a7b6 100644
--- a/java-checks-test-sources/default/src/main/java/checks/CollectorsToListCheckSample.java
+++ b/java-checks-test-sources/default/src/main/java/checks/CollectorsToListCheckSample.java
@@ -119,6 +119,26 @@ void compliant() {
       .collect(Collectors.toList()); // Compliant, list5 needs to be mutable
 
     list5.removeIf(s -> true);
+
+    List<String> list6 = Stream.of("B", "C", "D")
+      .collect(Collectors.toList()); // Compliant, list6 needs to be mutable
+
+    list6.addFirst("A");
+
+    List<String> list7 = Stream.of("A", "B", "C")
+      .collect(Collectors.toList()); // Compliant, list7 needs to be mutable
+
+    list7.addLast("D");
+
+    List<String> list8 = Stream.of("A", "B", "C")
+      .collect(Collectors.toList()); // Compliant, list8 needs to be mutable
+
+    list8.removeFirst();
+
+    List<String> list9 = Stream.of("A", "B", "C")
+      .collect(Collectors.toList()); // Compliant, list9 needs to be mutable
+
+    list9.removeLast();
   }
 
   void addX() {
diff --git a/java-checks/src/main/java/org/sonar/java/checks/CollectorsToListCheck.java b/java-checks/src/main/java/org/sonar/java/checks/CollectorsToListCheck.java
index 4dfcb43ddb4..e6c55758f04 100644
--- a/java-checks/src/main/java/org/sonar/java/checks/CollectorsToListCheck.java
+++ b/java-checks/src/main/java/org/sonar/java/checks/CollectorsToListCheck.java
@@ -58,7 +58,8 @@ public class CollectorsToListCheck extends AbstractMethodDetection implements Ja
 
   private static final MethodMatchers LIST_MODIFICATION_METHODS = MethodMatchers.create()
     .ofSubTypes("java.util.List")
-    .names("add", "addAll", "remove", "removeAll", "retainAll", "replaceAll", "set", "sort", "clear", "removeIf")
+    .names("add", "addAll", "remove", "removeAll", "retainAll", "replaceAll", "set", "sort", "clear", "removeIf",
+      "addFirst", "addLast", "removeFirst", "removeLast")
     .withAnyParameters()
     .build();