Use new collections initializers

27 files changed, 59 insertions, 87 deletions

diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/component/ConfigServerInfo.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/component/ConfigServerInfo.java
index d515f0d0353..9da480e55c7 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/component/ConfigServerInfo.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/component/ConfigServerInfo.java
@@ -4,7 +4,6 @@ package com.yahoo.vespa.hosted.node.admin.component;
 import com.yahoo.vespa.athenz.api.AthenzIdentity;
 
 import java.net.URI;
-import java.util.Collections;
 import java.util.List;
 import java.util.function.Function;
 import java.util.stream.Collectors;
@@ -27,7 +26,7 @@ public class ConfigServerInfo {
         this.configServerHostnameToUriMapper = hostname -> URI.create(scheme + "://" + hostname + ":" + port);
         this.configServerURIs = configServerHostNames.stream()
                 .map(configServerHostnameToUriMapper)
-                .collect(Collectors.collectingAndThen(Collectors.toList(), Collections::unmodifiableList));
+                .collect(Collectors.toUnmodifiableList());
     }
 
     private static URI createLoadBalancerEndpoint(String loadBalancerHost, String scheme, int port) {
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/configserver/ConfigServerApiImpl.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/configserver/ConfigServerApiImpl.java
index a533556bde8..67dcb6744ce 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/configserver/ConfigServerApiImpl.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/configserver/ConfigServerApiImpl.java
@@ -77,7 +77,7 @@ public class ConfigServerApiImpl implements ConfigServerApi {
                                                 HostnameVerifier hostnameVerifier,
                                                 HostName configServerHostname) {
         return new ConfigServerApiImpl(
-                Collections.singleton(info.getConfigServerUri(configServerHostname.value())),
+                List.of(info.getConfigServerUri(configServerHostname.value())),
                 hostnameVerifier,
                 provider);
     }
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/configserver/noderepository/bindings/GetAclResponse.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/configserver/noderepository/bindings/GetAclResponse.java
index ea2f313f03a..2d59898dc52 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/configserver/noderepository/bindings/GetAclResponse.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/configserver/noderepository/bindings/GetAclResponse.java
@@ -5,7 +5,6 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 import com.fasterxml.jackson.annotation.JsonProperty;
 
-import java.util.Collections;
 import java.util.List;
 
 /**
@@ -29,9 +28,9 @@ public class GetAclResponse {
     public GetAclResponse(@JsonProperty("trustedNodes") List<Node> trustedNodes,
                           @JsonProperty("trustedNetworks") List<Network> trustedNetworks,
                           @JsonProperty("trustedPorts") List<Port> trustedPorts) {
-        this.trustedNodes = trustedNodes == null ? Collections.emptyList() : trustedNodes;
-        this.trustedNetworks = trustedNetworks == null ? Collections.emptyList() : trustedNetworks;
-        this.trustedPorts = trustedPorts == null ? Collections.emptyList() : trustedPorts;
+        this.trustedNodes = trustedNodes == null ? List.of() : trustedNodes;
+        this.trustedNetworks = trustedNetworks == null ? List.of() : trustedNetworks;
+        this.trustedPorts = trustedPorts == null ? List.of() : trustedPorts;
     }
 
     @JsonIgnoreProperties(ignoreUnknown = true)
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/NatTableLineEditor.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/NatTableLineEditor.java
index e1dc4a661ff..be08e1b2aec 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/NatTableLineEditor.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/NatTableLineEditor.java
@@ -4,8 +4,6 @@ package com.yahoo.vespa.hosted.node.admin.maintenance.acl;
 import com.yahoo.vespa.hosted.node.admin.task.util.file.LineEdit;
 import com.yahoo.vespa.hosted.node.admin.task.util.file.LineEditor;
 
-import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 
 /**
@@ -45,7 +43,7 @@ class NatTableLineEditor implements LineEditor {
 
     @Override
     public List<String> onComplete() {
-        if (redirectExists) return new ArrayList<>();
-        return Collections.singletonList(redirectRule);
+        if (redirectExists) return List.of();
+        return List.of(redirectRule);
     }
 }
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/coredump/CoreCollector.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/coredump/CoreCollector.java
index c063059e8a9..cdf5687d61a 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/coredump/CoreCollector.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/coredump/CoreCollector.java
@@ -82,7 +82,7 @@ public class CoreCollector {
         if (result.getExitStatus() != 0)
             throw new RuntimeException("Failed to read backtrace " + result + ", Command: " + Arrays.toString(command));
 
-        return Arrays.asList(result.getOutput().split("\n"));
+        return List.of(result.getOutput().split("\n"));
     }
 
     List<String> readJstack(NodeAgentContext context, Path coredumpPath, Path binPath) {
@@ -92,7 +92,7 @@ public class CoreCollector {
         if (result.getExitStatus() != 0)
             throw new RuntimeException("Failed to read jstack " + result + ", Command: " + Arrays.toString(command));
 
-        return Arrays.asList(result.getOutput().split("\n"));
+        return List.of(result.getOutput().split("\n"));
     }
 
     /**
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/coredump/CoredumpHandler.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/coredump/CoredumpHandler.java
index 2874546da52..9b0a35d4b96 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/coredump/CoredumpHandler.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/coredump/CoredumpHandler.java
@@ -2,7 +2,6 @@
 package com.yahoo.vespa.hosted.node.admin.maintenance.coredump;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
-import com.google.common.collect.ImmutableMap;
 import com.yahoo.vespa.hosted.node.admin.nodeagent.NodeAgentContext;
 import com.yahoo.vespa.hosted.node.admin.task.util.file.FileFinder;
 import com.yahoo.vespa.hosted.node.admin.task.util.file.UnixPath;
@@ -159,7 +158,7 @@ public class CoredumpHandler {
             Map<String, Object> metadata = coreCollector.collect(context, coredumpFilePathInContainer);
             metadata.putAll(nodeAttributesSupplier.get());
 
-            String metadataFields = objectMapper.writeValueAsString(ImmutableMap.of("fields", metadata));
+            String metadataFields = objectMapper.writeValueAsString(Map.of("fields", metadata));
             metadataPath.writeUtf8File(metadataFields);
             return metadataFields;
         } else {
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/identity/AthenzCredentialsMaintainer.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/identity/AthenzCredentialsMaintainer.java
index 17dc61978cf..4c5ad7c5c3a 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/identity/AthenzCredentialsMaintainer.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/maintenance/identity/AthenzCredentialsMaintainer.java
@@ -44,11 +44,10 @@ import java.time.Clock;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.logging.Logger;
 
-import static java.util.Collections.singleton;
-
 /**
  * A maintainer that is responsible for providing and refreshing Athenz credentials for a container.
  *
@@ -103,7 +102,7 @@ public class AthenzCredentialsMaintainer implements CredentialsMaintainer {
         this.identityDocumentClient = new DefaultIdentityDocumentClient(
                 configServerInfo.getLoadBalancerEndpoint(),
                 hostIdentityProvider,
-                new AthenzIdentityVerifier(singleton(configserverIdentity)));
+                new AthenzIdentityVerifier(Set.of(configserverIdentity)));
         this.clock = clock;
         this.useInternalZts = useInternalZts;
     }
@@ -194,7 +193,7 @@ public class AthenzCredentialsMaintainer implements CredentialsMaintainer {
 
         // Set up a hostname verified for zts if this is configured to use the config server (internal zts) apis
         HostnameVerifier ztsHostNameVerifier = useInternalZts
-                ? new AthenzIdentityVerifier(singleton(configserverIdentity))
+                ? new AthenzIdentityVerifier(Set.of(configserverIdentity))
                 : null;
         try (ZtsClient ztsClient = new DefaultZtsClient(ztsEndpoint, hostIdentityProvider, ztsHostNameVerifier)) {
             InstanceIdentity instanceIdentity =
@@ -223,7 +222,7 @@ public class AthenzCredentialsMaintainer implements CredentialsMaintainer {
         try {
             // Set up a hostname verified for zts if this is configured to use the config server (internal zts) apis
             HostnameVerifier ztsHostNameVerifier = useInternalZts
-                    ? new AthenzIdentityVerifier(singleton(configserverIdentity))
+                    ? new AthenzIdentityVerifier(Set.of(configserverIdentity))
                     : null;
             try (ZtsClient ztsClient = new DefaultZtsClient(ztsEndpoint, containerIdentitySslContext, ztsHostNameVerifier)) {
                 InstanceIdentity instanceIdentity =
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/editor/CursorImpl.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/editor/CursorImpl.java
index 47c710395f5..22972a9f15b 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/editor/CursorImpl.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/editor/CursorImpl.java
@@ -1,8 +1,7 @@
 // Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-
 package com.yahoo.vespa.hosted.node.admin.task.util.editor;
 
-import java.util.Arrays;
+import java.util.List;
 import java.util.Optional;
 import java.util.function.Consumer;
 import java.util.function.Function;
@@ -223,7 +222,7 @@ public class CursorImpl implements Cursor {
 
     @Override
     public Cursor writeLines(String... lines) {
-        return writeLines(Arrays.asList(lines));
+        return writeLines(List.of(lines));
     }
 
     @Override
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/FileFinder.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/FileFinder.java
index b78d155bdbf..f10ebd5e315 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/FileFinder.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/FileFinder.java
@@ -14,9 +14,9 @@ import java.nio.file.attribute.BasicFileAttributes;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Set;
 import java.util.Stack;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
@@ -139,7 +139,7 @@ public class FileFinder {
         try {
             // Only need to traverse as deep as we want to match, unless we want to match everything in directories
             // already matched
-            Files.walkFileTree(basePath, Collections.emptySet(), maxDepth, new SimpleFileVisitor<>() {
+            Files.walkFileTree(basePath, Set.of(), maxDepth, new SimpleFileVisitor<>() {
                 private final Stack<FileAttributes> matchingDirectoryStack = new Stack<>();
                 private int currentLevel = -1;
 
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/LineEdit.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/LineEdit.java
index 78e7a3e71b6..88bf25c65a9 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/LineEdit.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/LineEdit.java
@@ -1,11 +1,7 @@
 // Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.hosted.node.admin.task.util.file;
 
-import com.google.common.collect.ImmutableList;
-
 import javax.annotation.concurrent.Immutable;
-import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 
 import static com.yahoo.vespa.hosted.node.admin.task.util.file.LineEdit.Type.REPLACE;
@@ -18,17 +14,17 @@ import static com.yahoo.vespa.hosted.node.admin.task.util.file.LineEdit.Type.NON
 public class LineEdit {
     enum Type { NONE, REPLACE }
 
-    public static LineEdit none() { return insert(Collections.emptyList(), Collections.emptyList()); }
-    public static LineEdit remove() { return replaceWith(Collections.emptyList()); }
+    public static LineEdit none() { return insert(List.of(), List.of()); }
+    public static LineEdit remove() { return replaceWith(List.of()); }
 
-    public static LineEdit insertBefore(String... prepend) { return insertBefore(Arrays.asList(prepend)); }
-    public static LineEdit insertBefore(List<String> prepend) { return insert(prepend, Collections.emptyList()); }
-    public static LineEdit insertAfter(String... append) { return insertAfter(Arrays.asList(append)); }
-    public static LineEdit insertAfter(List<String> append) { return insert(Collections.emptyList(), append); }
+    public static LineEdit insertBefore(String... prepend) { return insertBefore(List.of(prepend)); }
+    public static LineEdit insertBefore(List<String> prepend) { return insert(prepend, List.of()); }
+    public static LineEdit insertAfter(String... append) { return insertAfter(List.of(append)); }
+    public static LineEdit insertAfter(List<String> append) { return insert(List.of(), append); }
     public static LineEdit insert(List<String> prepend, List<String> append) { return new LineEdit(NONE, prepend, append); }
 
-    public static LineEdit replaceWith(String... lines) { return replaceWith(Arrays.asList(lines)); }
-    public static LineEdit replaceWith(List<String> insertLines) { return new LineEdit(REPLACE, Collections.emptyList(), insertLines); }
+    public static LineEdit replaceWith(String... lines) { return replaceWith(List.of(lines)); }
+    public static LineEdit replaceWith(List<String> insertLines) { return new LineEdit(REPLACE, List.of(), insertLines); }
 
     private final Type type;
     private final List<String> prependLines;
@@ -36,8 +32,8 @@ public class LineEdit {
 
     private LineEdit(Type type, List<String> prependLines, List<String> appendLines) {
         this.type = type;
-        this.prependLines = ImmutableList.copyOf(prependLines);
-        this.appendLines = ImmutableList.copyOf(appendLines);
+        this.prependLines = List.copyOf(prependLines);
+        this.appendLines = List.copyOf(appendLines);
     }
 
     public Type getType() { return type; }
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/UnixPath.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/UnixPath.java
index 668c2787513..268e0a5ccfd 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/UnixPath.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/file/UnixPath.java
@@ -19,7 +19,6 @@ import java.nio.file.attribute.PosixFilePermissions;
 import java.nio.file.attribute.UserPrincipal;
 import java.nio.file.attribute.UserPrincipalLookupService;
 import java.time.Instant;
-import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
@@ -217,7 +216,7 @@ public class UnixPath {
                     .map(UnixPath::new)
                     .collect(Collectors.toList());
         } catch (NoSuchFileException ignored) {
-            return Collections.emptyList();
+            return List.of();
         } catch (IOException e) {
             throw new RuntimeException("Failed to list contents of directory " + path.toAbsolutePath(), e);
         }
diff --git a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/process/CommandLine.java b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/process/CommandLine.java
index 8f39c2d257b..d86c8745ceb 100644
--- a/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/process/CommandLine.java
+++ b/node-admin/src/main/java/com/yahoo/vespa/hosted/node/admin/task/util/process/CommandLine.java
@@ -9,7 +9,6 @@ import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
 import java.time.Duration;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
@@ -67,7 +66,7 @@ public class CommandLine {
     }
 
     /** Add arguments to the command. The first argument in the first call to add() is the program. */
-    public CommandLine add(String... arguments) { return add(Arrays.asList(arguments)); }
+    public CommandLine add(String... arguments) { return add(List.of(arguments)); }
 
     /** Add arguments to the command. The first argument in the first call to add() is the program. */
     public CommandLine add(Collection<String> arguments) {
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/ConfigServerApiImplTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/ConfigServerApiImplTest.java
index 0909a03749e..84a9c7a0a7d 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/ConfigServerApiImplTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/ConfigServerApiImplTest.java
@@ -19,7 +19,6 @@ import java.net.SocketTimeoutException;
 import java.net.URI;
 import java.nio.charset.StandardCharsets;
 import java.time.Duration;
-import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
 
@@ -54,7 +53,7 @@ public class ConfigServerApiImplTest {
 
     private final String uri1 = "http://host1:666";
     private final String uri2 = "http://host2:666";
-    private final List<URI> configServers = Arrays.asList(URI.create(uri1), URI.create(uri2));
+    private final List<URI> configServers = List.of(URI.create(uri1), URI.create(uri2));
     private final StringBuilder mockLog = new StringBuilder();
 
     private ConfigServerApiImpl configServerApi;
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/noderepository/AclTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/noderepository/AclTest.java
index 3010586e708..341f2b8ca02 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/noderepository/AclTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/noderepository/AclTest.java
@@ -5,7 +5,6 @@ import com.yahoo.vespa.hosted.node.admin.task.util.network.IPVersion;
 import org.junit.Test;
 
 import java.util.Arrays;
-import java.util.Collections;
 import java.util.Set;
 import java.util.stream.Collectors;
 
@@ -20,12 +19,12 @@ public class AclTest {
     private static final Acl aclCommon = new Acl(
             Set.of(1234, 453),
             testNodes("192.1.2.2", "fb00::1", "fe80::2", "fe80::3"),
-            Collections.emptySet());
+            Set.of());
 
     private static final Acl aclWithoutPorts = new Acl(
-            Collections.emptySet(),
+            Set.of(),
             testNodes("192.1.2.2", "fb00::1", "fe80::2"),
-            Collections.emptySet());
+            Set.of());
 
     @Test
     public void no_trusted_ports() {
@@ -80,7 +79,7 @@ public class AclTest {
         Acl aclCommonDifferentOrder = new Acl(
                 Set.of(453, 1234),
                 testNodes("fe80::2", "192.1.2.2", "fb00::1", "fe80::3"),
-                Collections.emptySet());
+                Set.of());
 
         for (IPVersion ipVersion: IPVersion.values()) {
             assertEquals(aclCommon.toRules(ipVersion), aclCommonDifferentOrder.toRules(ipVersion));
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/noderepository/RealNodeRepositoryTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/noderepository/RealNodeRepositoryTest.java
index 9b392395045..4e0fd95384c 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/noderepository/RealNodeRepositoryTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/noderepository/RealNodeRepositoryTest.java
@@ -18,7 +18,6 @@ import java.io.IOException;
 import java.net.ServerSocket;
 import java.net.URI;
 import java.time.Instant;
-import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
@@ -67,7 +66,7 @@ public class RealNodeRepositoryTest {
                 int port = findRandomOpenPort();
                 container = JDisc.fromServicesXml(ContainerConfig.servicesXmlV2(port), Networking.enable);
                 ConfigServerApi configServerApi = ConfigServerApiImpl.createForTesting(
-                        Collections.singletonList(URI.create("http://127.0.0.1:" + port)));
+                        List.of(URI.create("http://127.0.0.1:" + port)));
                 waitForJdiscContainerToServe(configServerApi);
                 return;
             } catch (RuntimeException e) {
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/orchestrator/OrchestratorImplTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/orchestrator/OrchestratorImplTest.java
index 936a7bb224d..d118da07247 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/orchestrator/OrchestratorImplTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/configserver/orchestrator/OrchestratorImplTest.java
@@ -8,7 +8,6 @@ import com.yahoo.vespa.orchestrator.restapi.wire.HostStateChangeDenialReason;
 import com.yahoo.vespa.orchestrator.restapi.wire.UpdateHostResponse;
 import org.junit.Test;
 
-import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
 
@@ -109,7 +108,7 @@ public class OrchestratorImplTest {
     @Test
     public void testBatchSuspendCall() {
         String parentHostName = "host1.test.yahoo.com";
-        List<String> hostNames = Arrays.asList("a1.host1.test.yahoo.com", "a2.host1.test.yahoo.com");
+        List<String> hostNames = List.of("a1.host1.test.yahoo.com", "a2.host1.test.yahoo.com");
 
         when(configServerApi.put(
                 eq("/orchestrator/v1/suspensions/hosts/host1.test.yahoo.com?hostname=a1.host1.test.yahoo.com&hostname=a2.host1.test.yahoo.com"),
@@ -124,7 +123,7 @@ public class OrchestratorImplTest {
     @Test(expected=OrchestratorException.class)
     public void testBatchSuspendCallWithFailureReason() {
         String parentHostName = "host1.test.yahoo.com";
-        List<String> hostNames = Arrays.asList("a1.host1.test.yahoo.com", "a2.host1.test.yahoo.com");
+        List<String> hostNames = List.of("a1.host1.test.yahoo.com", "a2.host1.test.yahoo.com");
         String failureReason = "Failed to suspend";
 
         when(configServerApi.put(
@@ -140,7 +139,7 @@ public class OrchestratorImplTest {
     @Test(expected=RuntimeException.class)
     public void testBatchSuspendCallWithSomeException() {
         String parentHostName = "host1.test.yahoo.com";
-        List<String> hostNames = Arrays.asList("a1.host1.test.yahoo.com", "a2.host1.test.yahoo.com");
+        List<String> hostNames = List.of("a1.host1.test.yahoo.com", "a2.host1.test.yahoo.com");
         String exceptionMessage = "Exception: Something crashed!";
 
         when(configServerApi.put(
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/integrationTests/NodeRepoMock.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/integrationTests/NodeRepoMock.java
index 625166a10d2..80069b38748 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/integrationTests/NodeRepoMock.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/integrationTests/NodeRepoMock.java
@@ -8,7 +8,6 @@ import com.yahoo.vespa.hosted.node.admin.configserver.noderepository.NodeReposit
 import com.yahoo.vespa.hosted.node.admin.configserver.noderepository.NodeSpec;
 import com.yahoo.vespa.hosted.node.admin.configserver.noderepository.NodeState;
 
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -46,7 +45,7 @@ public class NodeRepoMock implements NodeRepository {
 
     @Override
     public Map<String, Acl> getAcls(String hostname) {
-        return Collections.emptyMap();
+        return Map.of();
     }
 
     @Override
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/integrationTests/RebootTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/integrationTests/RebootTest.java
index 4a232a5b2bd..d1778982043 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/integrationTests/RebootTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/integrationTests/RebootTest.java
@@ -10,7 +10,7 @@ import com.yahoo.vespa.hosted.node.admin.configserver.noderepository.NodeState;
 import com.yahoo.vespa.hosted.node.admin.nodeadmin.NodeAdminStateUpdater;
 import org.junit.Test;
 
-import java.util.Arrays;
+import java.util.List;
 import java.util.OptionalLong;
 
 import static com.yahoo.vespa.hosted.node.admin.integrationTests.DockerTester.HOST_HOSTNAME;
@@ -40,7 +40,7 @@ public class RebootTest {
             } catch (RuntimeException ignored) { }
 
             tester.inOrder(tester.orchestrator).suspend(
-                    eq(HOST_HOSTNAME.value()), eq(Arrays.asList(hostname, HOST_HOSTNAME.value())));
+                    eq(HOST_HOSTNAME.value()), eq(List.of(hostname, HOST_HOSTNAME.value())));
             tester.inOrder(tester.docker).executeInContainerAsUser(
                     eq(new ContainerName("host1")), eq("root"), eq(OptionalLong.empty()), eq(NODE_PROGRAM), eq("stop"));
             assertTrue(tester.nodeAdmin.setFrozen(true));
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/AclMaintainerTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/AclMaintainerTest.java
index 90674f86907..adecc370b85 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/AclMaintainerTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/AclMaintainerTest.java
@@ -15,8 +15,6 @@ import org.junit.Test;
 
 import java.nio.file.FileSystem;
 import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 import java.util.function.Function;
 
@@ -70,7 +68,7 @@ public class AclMaintainerTest {
         verify(dockerOperations, times(2)).executeCommandInNetworkNamespace(eq(context), eq("ip6tables-restore"), any());
         verifyNoMoreInteractions(dockerOperations);
 
-        List<String> expected = Arrays.asList(
+        List<String> expected = List.of(
                 // IPv4 filter table restore
                 "*filter\n" +
                 "-P INPUT ACCEPT\n" +
@@ -137,7 +135,7 @@ public class AclMaintainerTest {
         verify(dockerOperations, times(1)).executeCommandInNetworkNamespace(eq(context), eq("ip6tables-restore"), any());
         verifyNoMoreInteractions(dockerOperations);
 
-        List<String> expected = Arrays.asList(
+        List<String> expected = List.of(
                 // IPv4 filter table restore
                 "*filter\n" +
                 "-P INPUT ACCEPT\n" +
@@ -194,7 +192,7 @@ public class AclMaintainerTest {
         verify(dockerOperations, never()).executeCommandInNetworkNamespace(eq(context), eq("ip6tables-restore"), any()); //we don't have a ip4 address for the container so no redirect
         verifyNoMoreInteractions(dockerOperations);
 
-        List<String> expected = Collections.singletonList(
+        List<String> expected = List.of(
                 "*filter\n" +
                 "-P INPUT ACCEPT\n" +
                 "-P FORWARD ACCEPT\n" +
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/FilterTableLineEditorTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/FilterTableLineEditorTest.java
index f72cde92839..192422492c8 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/FilterTableLineEditorTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/FilterTableLineEditorTest.java
@@ -6,7 +6,7 @@ import com.yahoo.vespa.hosted.node.admin.task.util.file.Editor;
 import com.yahoo.vespa.hosted.node.admin.task.util.network.IPVersion;
 import org.junit.Test;
 
-import java.util.Arrays;
+import java.util.List;
 
 import static org.junit.Assert.assertEquals;
 
@@ -42,7 +42,7 @@ public class FilterTableLineEditorTest {
         FilterTableLineEditor filterLineEditor = FilterTableLineEditor.from(acl, ipVersion);
         Editor editor = new Editor(
                 "nat-table",
-                () -> Arrays.asList(currentFilterTable.split("\n")),
+                () -> List.of(currentFilterTable.split("\n")),
                 result -> assertEquals(expectedRestoreFileContent, String.join("\n", result)),
                 filterLineEditor);
         editor.edit(m -> {});
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/NatTableLineEditorTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/NatTableLineEditorTest.java
index 63dc69a180c..1ea3658db76 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/NatTableLineEditorTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/maintenance/acl/NatTableLineEditorTest.java
@@ -4,7 +4,7 @@ package com.yahoo.vespa.hosted.node.admin.maintenance.acl;
 import com.yahoo.vespa.hosted.node.admin.task.util.file.Editor;
 import org.junit.Test;
 
-import java.util.Arrays;
+import java.util.List;
 
 import static org.junit.Assert.assertEquals;
 
@@ -88,7 +88,7 @@ public class NatTableLineEditorTest {
         NatTableLineEditor natLineEditor = NatTableLineEditor.from(redirectRule);
         Editor editor = new Editor(
                 "nat-table",
-                () -> Arrays.asList(currentNatTable.split("\n")),
+                () -> List.of(currentNatTable.split("\n")),
                 result -> assertEquals(expectedNatTable, String.join("\n", result)),
                 natLineEditor);
         editor.edit(m -> {});
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/provider/DebugHandlerHelperTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/provider/DebugHandlerHelperTest.java
index a930e2babff..afb0c86ba2a 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/provider/DebugHandlerHelperTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/provider/DebugHandlerHelperTest.java
@@ -1,10 +1,9 @@
 // Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-
 package com.yahoo.vespa.hosted.node.admin.provider;
 
 import org.junit.Test;
 
-import java.util.Collections;
+import java.util.Map;
 
 import static org.junit.Assert.assertEquals;
 
@@ -14,7 +13,7 @@ public class DebugHandlerHelperTest {
         DebugHandlerHelper helper = new DebugHandlerHelper();
         helper.addConstant("constant-key", "constant-value");
 
-        NodeAdminDebugHandler handler = () -> Collections.singletonMap("handler-value-key", "handler-value-value");
+        NodeAdminDebugHandler handler = () -> Map.of("handler-value-key", "handler-value-value");
         helper.addHandler("handler-key", handler);
 
         helper.addThreadSafeSupplier("supplier-key", () -> "supplier-value");
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/EditorTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/EditorTest.java
index 3d492c41d0f..70e9ae50584 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/EditorTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/EditorTest.java
@@ -1,5 +1,4 @@
 // Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-
 package com.yahoo.vespa.hosted.node.admin.task.util.file;
 
 import com.yahoo.vespa.hosted.node.admin.component.TaskContext;
@@ -8,7 +7,6 @@ import org.junit.Test;
 import org.mockito.ArgumentCaptor;
 
 import java.nio.file.FileSystem;
-import java.util.Collections;
 import java.util.List;
 
 import static org.junit.Assert.assertEquals;
@@ -62,8 +60,8 @@ public class EditorTest {
                 LineEdit.insertBefore("first"), // insert first, and keep the second line
                 LineEdit.replaceWith("third", "fourth"), // remove eight, and replace with third and fourth instead
                 LineEdit.none(), // Keep fifth
-                LineEdit.insert(Collections.singletonList("sixth"), // insert sixth before seventh
-                        Collections.singletonList("eight"))); // add eight after seventh
+                LineEdit.insert(List.of("sixth"), // insert sixth before seventh
+                        List.of("eight"))); // add eight after seventh
 
         Editor editor = new Editor(path.toPath(), lineEditor);
         TaskContext context = mock(TaskContext.class);
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/FileFinderTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/FileFinderTest.java
index 1308e4ead8c..197077159d1 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/FileFinderTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/FileFinderTest.java
@@ -19,7 +19,6 @@ import java.nio.file.attribute.BasicFileAttributes;
 import java.nio.file.attribute.FileTime;
 import java.time.Duration;
 import java.time.Instant;
-import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Set;
@@ -157,7 +156,7 @@ public class FileFinderTest {
                 });
                 return paths;
             } catch (NoSuchFileException e) {
-                return Collections.emptyList();
+                return List.of();
             } catch (IOException e) {
                 throw new UncheckedIOException(e);
             }
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/FileSyncTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/FileSyncTest.java
index a141faf290b..cbf471bd611 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/FileSyncTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/FileSyncTest.java
@@ -11,7 +11,6 @@ import java.nio.file.Files;
 import java.nio.file.Path;
 import java.time.Instant;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.List;
 
 import static org.junit.Assert.assertArrayEquals;
@@ -71,7 +70,7 @@ public class FileSyncTest {
         fileData.getPermissions().ifPresent(permissions -> assertEquals(permissions, unixPath.getPermissions()));
 
         List<String> actualMods = taskContext.getSystemModificationLog();
-        List<String> expectedMods = Arrays.asList(systemModificationMessages);
+        List<String> expectedMods = List.of(systemModificationMessages);
         assertEquals(expectedMods, actualMods);
 
         UnixPath unixPath = new UnixPath(path);
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/MakeDirectoryTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/MakeDirectoryTest.java
index b714ab539f6..c28aa6faa30 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/MakeDirectoryTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/file/MakeDirectoryTest.java
@@ -1,5 +1,4 @@
 // Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-
 package com.yahoo.vespa.hosted.node.admin.task.util.file;
 
 import com.yahoo.vespa.hosted.node.admin.component.TestTaskContext;
@@ -10,8 +9,7 @@ import java.io.UncheckedIOException;
 import java.nio.file.FileSystem;
 import java.nio.file.Files;
 import java.nio.file.NoSuchFileException;
-import java.util.Arrays;
-import java.util.Collections;
+import java.util.List;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -56,11 +54,11 @@ public class MakeDirectoryTest {
                 .withGroup(group);
         assertTrue(makeDirectory.converge(context));
 
-        assertEquals(Arrays.asList(modifications), context.getSystemModificationLog());
+        assertEquals(List.of(modifications), context.getSystemModificationLog());
 
         context.clearSystemModificationLog();
         assertFalse(makeDirectory.converge(context));
-        assertEquals(Collections.emptyList(), context.getSystemModificationLog());
+        assertEquals(List.of(), context.getSystemModificationLog());
     }
 
     @Test
diff --git a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/process/CommandLineTest.java b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/process/CommandLineTest.java
index 7bdf9a44ec7..6dd5087e8a0 100644
--- a/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/process/CommandLineTest.java
+++ b/node-admin/src/test/java/com/yahoo/vespa/hosted/node/admin/task/util/process/CommandLineTest.java
@@ -6,7 +6,6 @@ import org.junit.After;
 import org.junit.Test;
 
 import java.nio.charset.StandardCharsets;
-import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
 import java.util.function.Predicate;
@@ -43,7 +42,7 @@ public class CommandLineTest {
         assertEquals(0, result.getExitCode());
         assertEquals("line1\nline2", result.getOutput());
         assertEquals("line1\nline2\n\n", result.getUntrimmedOutput());
-        assertEquals(Arrays.asList("line1", "line2"), result.getOutputLines());
+        assertEquals(List.of("line1", "line2"), result.getOutputLines());
         assertEquals(1, context.getSystemModificationLog().size());
         assertEquals("Executing command: foo bar 2>&1", context.getSystemModificationLog().get(0));