diff --git a/server/src/test/java/org/elasticsearch/action/admin/cluster/node/tasks/RecordingTaskManagerListener.java b/server/src/test/java/org/elasticsearch/action/admin/cluster/node/tasks/RecordingTaskManagerListener.java
index 5a88df80ae6ed..e03fb3b60a54f 100644
--- a/server/src/test/java/org/elasticsearch/action/admin/cluster/node/tasks/RecordingTaskManagerListener.java
+++ b/server/src/test/java/org/elasticsearch/action/admin/cluster/node/tasks/RecordingTaskManagerListener.java
@@ -15,8 +15,8 @@
 import org.elasticsearch.test.tasks.MockTaskManagerListener;
 
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
+import java.util.function.Predicate;
 
 /**
  * MockTaskManagerListener that records all task registration/unregistration events
@@ -55,13 +55,11 @@ public synchronized List<Tuple<Boolean, TaskInfo>> getEvents() {
     }
 
     public synchronized List<TaskInfo> getRegistrationEvents() {
-        List<TaskInfo> events = this.events.stream().filter(Tuple::v1).map(Tuple::v2).toList();
-        return Collections.unmodifiableList(events);
+        return this.events.stream().filter(Tuple::v1).map(Tuple::v2).toList();
     }
 
     public synchronized List<TaskInfo> getUnregistrationEvents() {
-        List<TaskInfo> events = this.events.stream().filter(event -> event.v1() == false).map(Tuple::v2).toList();
-        return Collections.unmodifiableList(events);
+        return this.events.stream().filter(Predicate.not(Tuple::v1)).map(Tuple::v2).toList();
     }
 
     public synchronized void reset() {
diff --git a/server/src/test/java/org/elasticsearch/action/admin/cluster/storedscripts/ScriptContextInfoSerializingTests.java b/server/src/test/java/org/elasticsearch/action/admin/cluster/storedscripts/ScriptContextInfoSerializingTests.java
index 0fb7f966fb017..f2573dc024180 100644
--- a/server/src/test/java/org/elasticsearch/action/admin/cluster/storedscripts/ScriptContextInfoSerializingTests.java
+++ b/server/src/test/java/org/elasticsearch/action/admin/cluster/storedscripts/ScriptContextInfoSerializingTests.java
@@ -67,8 +67,8 @@ private static ScriptContextInfo mutate(ScriptContextInfo instance, Set<String>
     }
 
     static Set<ScriptContextInfo> mutateOne(Collection<ScriptContextInfo> instances) {
-        if (instances.size() == 0) {
-            return Collections.unmodifiableSet(Set.of(randomInstance()));
+        if (instances.isEmpty()) {
+            return Set.of(randomInstance());
         }
         ArrayList<ScriptContextInfo> mutated = new ArrayList<>(instances);
         int mutateIndex = randomIntBetween(0, instances.size() - 1);
diff --git a/server/src/test/java/org/elasticsearch/action/admin/cluster/storedscripts/ScriptParameterInfoSerializingTests.java b/server/src/test/java/org/elasticsearch/action/admin/cluster/storedscripts/ScriptParameterInfoSerializingTests.java
index cefd1488eddef..906a8ce9e08d2 100644
--- a/server/src/test/java/org/elasticsearch/action/admin/cluster/storedscripts/ScriptParameterInfoSerializingTests.java
+++ b/server/src/test/java/org/elasticsearch/action/admin/cluster/storedscripts/ScriptParameterInfoSerializingTests.java
@@ -54,8 +54,8 @@ private static ParameterInfo mutate(ParameterInfo instance) {
     }
 
     static List<ParameterInfo> mutateOne(List<ParameterInfo> instances) {
-        if (instances.size() == 0) {
-            return Collections.unmodifiableList(List.of(randomInstance()));
+        if (instances.isEmpty()) {
+            return List.of(randomInstance());
         }
         ArrayList<ParameterInfo> mutated = new ArrayList<>(instances);
         int mutateIndex = randomIntBetween(0, instances.size() - 1);