Remove unnecessary NodeVersions class

16 files changed, 71 insertions, 163 deletions

diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/maintenance/MetricsReporter.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/maintenance/MetricsReporter.java
index 3f65c2e49cd..e23cda4dae0 100644
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/maintenance/MetricsReporter.java
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/maintenance/MetricsReporter.java
@@ -9,7 +9,6 @@ import com.yahoo.jdisc.Metric;
 import com.yahoo.vespa.hosted.controller.Application;
 import com.yahoo.vespa.hosted.controller.Controller;
 import com.yahoo.vespa.hosted.controller.Instance;
-import com.yahoo.vespa.hosted.controller.api.integration.billing.PlanId;
 import com.yahoo.vespa.hosted.controller.api.integration.deployment.ApplicationVersion;
 import com.yahoo.vespa.hosted.controller.application.ApplicationList;
 import com.yahoo.vespa.hosted.controller.application.Deployment;
@@ -19,7 +18,6 @@ import com.yahoo.vespa.hosted.controller.deployment.DeploymentStatusList;
 import com.yahoo.vespa.hosted.controller.deployment.JobList;
 import com.yahoo.vespa.hosted.controller.rotation.RotationLock;
 import com.yahoo.vespa.hosted.controller.versions.NodeVersion;
-import com.yahoo.vespa.hosted.controller.versions.NodeVersions;
 import com.yahoo.vespa.hosted.controller.versions.VersionStatus;
 import com.yahoo.vespa.hosted.controller.versions.VespaVersion;
 
@@ -221,11 +219,11 @@ public class MetricsReporter extends ControllerMaintainer {
         return changeDurations(controller().osVersionStatus().versions().values(), Function.identity());
     }
 
-    private <V> Map<NodeVersion, Duration> changeDurations(Collection<V> versions, Function<V, NodeVersions> versionsGetter) {
+    private <V> Map<NodeVersion, Duration> changeDurations(Collection<V> versions, Function<V, List<NodeVersion>> versionsGetter) {
         var now = clock.instant();
         var durations = new HashMap<NodeVersion, Duration>();
         for (var version : versions) {
-            for (var nodeVersion : versionsGetter.apply(version).asMap().values()) {
+            for (var nodeVersion : versionsGetter.apply(version)) {
                 durations.put(nodeVersion, nodeVersion.changeDuration(now));
             }
         }
diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/NodeVersionSerializer.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/NodeVersionSerializer.java
index 2861e8922a5..857087ab0b3 100644
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/NodeVersionSerializer.java
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/NodeVersionSerializer.java
@@ -1,7 +1,6 @@
 // Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.hosted.controller.persistence;
 
-import com.google.common.collect.ImmutableMap;
 import com.yahoo.component.Version;
 import com.yahoo.config.provision.HostName;
 import com.yahoo.config.provision.zone.ZoneId;
@@ -10,7 +9,9 @@ import com.yahoo.slime.Cursor;
 import com.yahoo.slime.Inspector;
 import com.yahoo.slime.SlimeUtils;
 import com.yahoo.vespa.hosted.controller.versions.NodeVersion;
-import com.yahoo.vespa.hosted.controller.versions.NodeVersions;
+
+import java.util.ArrayList;
+import java.util.List;
 
 /**
  * Serializer for {@link com.yahoo.vespa.hosted.controller.versions.NodeVersion}.
@@ -31,8 +32,8 @@ public class NodeVersionSerializer {
     private static final String wantedVersionField = "wantedVersion";
     private static final String suspendedAtField = "suspendedAt";
 
-    public void nodeVersionsToSlime(NodeVersions nodeVersions, Cursor array) {
-        for (var nodeVersion : nodeVersions.asMap().values()) {
+    public void nodeVersionsToSlime(List<NodeVersion> nodeVersions, Cursor array) {
+        for (var nodeVersion : nodeVersions) {
             var nodeVersionObject = array.addObject();
             nodeVersionObject.setString(hostnameField, nodeVersion.hostname().value());
             nodeVersionObject.setString(zoneField, nodeVersion.zone().value());
@@ -42,16 +43,16 @@ public class NodeVersionSerializer {
         }
     }
 
-    public NodeVersions nodeVersionsFromSlime(Inspector array, Version version) {
-        var nodeVersions = ImmutableMap.<HostName, NodeVersion>builder();
+    public List<NodeVersion> nodeVersionsFromSlime(Inspector array, Version version) {
+        List<NodeVersion> nodeVersions = new ArrayList<>();
         array.traverse((ArrayTraverser) (i, entry) -> {
             var hostname = HostName.from(entry.field(hostnameField).asString());
             var zone = ZoneId.from(entry.field(zoneField).asString());
             var wantedVersion = Version.fromString(entry.field(wantedVersionField).asString());
             var suspendedAt = SlimeUtils.optionalInstant(entry.field(suspendedAtField));
-            nodeVersions.put(hostname, new NodeVersion(hostname, zone, version, wantedVersion, suspendedAt));
+            nodeVersions.add(new NodeVersion(hostname, zone, version, wantedVersion, suspendedAt));
         });
-        return new NodeVersions(nodeVersions.build());
+        return nodeVersions;
     }
 
 }
diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/OsVersionStatusSerializer.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/OsVersionStatusSerializer.java
index 8899ff89c0d..e2420993cb2 100644
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/OsVersionStatusSerializer.java
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/OsVersionStatusSerializer.java
@@ -7,10 +7,11 @@ import com.yahoo.slime.ArrayTraverser;
 import com.yahoo.slime.Cursor;
 import com.yahoo.slime.Inspector;
 import com.yahoo.slime.Slime;
-import com.yahoo.vespa.hosted.controller.versions.NodeVersions;
+import com.yahoo.vespa.hosted.controller.versions.NodeVersion;
 import com.yahoo.vespa.hosted.controller.versions.OsVersion;
 import com.yahoo.vespa.hosted.controller.versions.OsVersionStatus;
 
+import java.util.List;
 import java.util.Objects;
 
 /**
@@ -54,8 +55,8 @@ public class OsVersionStatusSerializer {
         return new OsVersionStatus(osVersionsFromSlime(slime.get().field(versionsField)));
     }
 
-    private ImmutableMap<OsVersion, NodeVersions> osVersionsFromSlime(Inspector array) {
-        var versions = ImmutableSortedMap.<OsVersion, NodeVersions>naturalOrder();
+    private ImmutableMap<OsVersion, List<NodeVersion>> osVersionsFromSlime(Inspector array) {
+        var versions = ImmutableSortedMap.<OsVersion, List<NodeVersion>>naturalOrder();
         array.traverse((ArrayTraverser) (i, object) -> {
             OsVersion osVersion = osVersionSerializer.fromSlime(object);
             versions.put(osVersion, nodeVersionSerializer.nodeVersionsFromSlime(object.field(nodeVersionsField), osVersion.version()));
diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/VersionStatusSerializer.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/VersionStatusSerializer.java
index eccda7332e1..0288a251798 100644
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/VersionStatusSerializer.java
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/persistence/VersionStatusSerializer.java
@@ -2,13 +2,12 @@
 package com.yahoo.vespa.hosted.controller.persistence;
 
 import com.yahoo.component.Version;
-import com.yahoo.config.provision.ApplicationId;
 import com.yahoo.slime.ArrayTraverser;
 import com.yahoo.slime.Cursor;
 import com.yahoo.slime.Inspector;
 import com.yahoo.slime.Slime;
 import com.yahoo.slime.SlimeUtils;
-import com.yahoo.vespa.hosted.controller.versions.NodeVersions;
+import com.yahoo.vespa.hosted.controller.versions.NodeVersion;
 import com.yahoo.vespa.hosted.controller.versions.VersionStatus;
 import com.yahoo.vespa.hosted.controller.versions.VespaVersion;
 
@@ -85,7 +84,7 @@ public class VersionStatusSerializer {
         nodeVersionsToSlime(version.nodeVersions(), object.setArray(nodeVersionsField));
     }
 
-    private void nodeVersionsToSlime(NodeVersions nodeVersions, Cursor array) {
+    private void nodeVersionsToSlime(List<NodeVersion> nodeVersions, Cursor array) {
         nodeVersionSerializer.nodeVersionsToSlime(nodeVersions, array);
     }
 
@@ -116,12 +115,4 @@ public class VersionStatusSerializer {
         );
     }
 
-    private List<ApplicationId> applicationsFromSlime(Inspector array) {
-        List<ApplicationId> applications = new ArrayList<>();
-        array.traverse((ArrayTraverser) (i, entry) -> applications.add(
-                ApplicationId.fromSerializedForm(entry.asString()))
-        );
-        return Collections.unmodifiableList(applications);
-    }
-
 }
diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/restapi/deployment/DeploymentApiHandler.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/restapi/deployment/DeploymentApiHandler.java
index 5d819ec9804..6ec0533c358 100644
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/restapi/deployment/DeploymentApiHandler.java
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/restapi/deployment/DeploymentApiHandler.java
@@ -4,7 +4,6 @@ package com.yahoo.vespa.hosted.controller.restapi.deployment;
 import com.yahoo.config.application.api.DeploymentInstanceSpec;
 import com.yahoo.config.application.api.DeploymentSpec;
 import com.yahoo.config.provision.ApplicationId;
-import com.yahoo.config.provision.HostName;
 import com.yahoo.container.jdisc.HttpRequest;
 import com.yahoo.container.jdisc.HttpResponse;
 import com.yahoo.container.jdisc.LoggingRequestHandler;
@@ -109,9 +108,9 @@ public class DeploymentApiHandler extends LoggingRequestHandler {
             versionObject.setBool("systemVersion", version.isSystemVersion());
 
             Cursor configServerArray = versionObject.setArray("configServers");
-            for (HostName hostname : version.nodeVersions().hostnames()) {
+            for (var nodeVersion : version.nodeVersions()) {
                 Cursor configServerObject = configServerArray.addObject();
-                configServerObject.setString("hostname", hostname.value());
+                configServerObject.setString("hostname", nodeVersion.hostname().value());
             }
 
             DeploymentStatistics statistics = deploymentStatistics.get(version.versionNumber());
diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/restapi/os/OsApiHandler.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/restapi/os/OsApiHandler.java
index b34c6685693..5a8e2c2fa62 100644
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/restapi/os/OsApiHandler.java
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/restapi/os/OsApiHandler.java
@@ -176,7 +176,7 @@ public class OsApiHandler extends AuditLoggingRequestHandler {
             target.ifPresent(t -> currentVersionObject.setString("upgradeBudget", t.upgradeBudget().toString()));
             currentVersionObject.setString("cloud", osVersion.cloud().value());
             Cursor nodesArray = currentVersionObject.setArray("nodes");
-            nodeVersions.asMap().values().forEach(nodeVersion -> {
+            nodeVersions.forEach(nodeVersion -> {
                 Cursor nodeObject = nodesArray.addObject();
                 nodeObject.setString("hostname", nodeVersion.hostname().value());
                 nodeObject.setString("environment", nodeVersion.zone().environment().value());
diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/NodeVersion.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/NodeVersion.java
index 15136ed79eb..8a1714e86d6 100644
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/NodeVersion.java
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/NodeVersion.java
@@ -61,7 +61,7 @@ public class NodeVersion {
         return Duration.between(suspendedAt.get(), instant).abs();
     }
 
-    /** The most recent time the node referenced by this suspended. This is empty if the node is not suspended. */
+    /** The most recent time the node referenced in this suspended. This is empty if the node is not suspended. */
     public Optional<Instant> suspendedAt() {
         return suspendedAt;
     }
diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/NodeVersions.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/NodeVersions.java
deleted file mode 100644
index e2791c0bfe5..00000000000
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/NodeVersions.java
+++ /dev/null
@@ -1,77 +0,0 @@
-// Copyright 2019 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-package com.yahoo.vespa.hosted.controller.versions;
-
-import com.google.common.collect.ImmutableMap;
-import com.yahoo.component.Version;
-import com.yahoo.config.provision.HostName;
-
-import java.util.Collection;
-import java.util.List;
-import java.util.Map;
-import java.util.Objects;
-import java.util.Set;
-import java.util.function.Predicate;
-
-/**
- * A filterable list of {@link NodeVersion}s. This is immutable.
- *
- * @author mpolden
- */
-public class NodeVersions {
-
-    private final ImmutableMap<HostName, NodeVersion> nodeVersions;
-
-    public NodeVersions(Map<HostName, NodeVersion> nodeVersions) {
-        this.nodeVersions = ImmutableMap.copyOf(Objects.requireNonNull(nodeVersions));
-    }
-
-    public Map<HostName, NodeVersion> asMap() {
-        return nodeVersions;
-    }
-
-    /** Returns host names in this */
-    public Set<HostName> hostnames() {
-        return nodeVersions.keySet();
-    }
-
-    /** Returns a copy of this containing only node versions of given version */
-    public NodeVersions matching(Version version) {
-        return copyOf(nodeVersions.values(), nodeVersion -> nodeVersion.currentVersion().equals(version));
-    }
-
-    /** Returns number of node versions in this */
-    public int size() {
-        return nodeVersions.size();
-    }
-
-    @Override
-    public boolean equals(Object o) {
-        if (this == o) return true;
-        if (o == null || getClass() != o.getClass()) return false;
-        NodeVersions that = (NodeVersions) o;
-        return nodeVersions.equals(that.nodeVersions);
-    }
-
-    @Override
-    public int hashCode() {
-        return Objects.hash(nodeVersions);
-    }
-
-    public static NodeVersions copyOf(List<NodeVersion> nodeVersions) {
-        return copyOf(nodeVersions, (ignored) -> true);
-    }
-
-    public static NodeVersions copyOf(Map<HostName, NodeVersion> nodeVersions) {
-        return new NodeVersions(nodeVersions);
-    }
-
-    private static NodeVersions copyOf(Collection<NodeVersion> nodeVersions, Predicate<NodeVersion> predicate) {
-        var newNodeVersions = ImmutableMap.<HostName, NodeVersion>builder();
-        for (var nodeVersion : nodeVersions) {
-            if (!predicate.test(nodeVersion)) continue;
-            newNodeVersions.put(nodeVersion.hostname(), nodeVersion);
-        }
-        return new NodeVersions(newNodeVersions.build());
-    }
-
-}
diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/OsVersionStatus.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/OsVersionStatus.java
index 69808a987fc..78c7b36181e 100644
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/OsVersionStatus.java
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/OsVersionStatus.java
@@ -4,18 +4,19 @@ package com.yahoo.vespa.hosted.controller.versions;
 import com.google.common.collect.ImmutableMap;
 import com.yahoo.component.Version;
 import com.yahoo.config.provision.CloudName;
-import com.yahoo.config.provision.HostName;
 import com.yahoo.config.provision.zone.ZoneApi;
 import com.yahoo.vespa.hosted.controller.Controller;
 import com.yahoo.vespa.hosted.controller.application.SystemApplication;
 import com.yahoo.vespa.hosted.controller.maintenance.OsUpgrader;
 
+import java.time.Instant;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.Set;
 import java.util.stream.Collectors;
 
@@ -28,15 +29,15 @@ public class OsVersionStatus {
 
     public static final OsVersionStatus empty = new OsVersionStatus(ImmutableMap.of());
 
-    private final Map<OsVersion, NodeVersions> versions;
+    private final Map<OsVersion, List<NodeVersion>> versions;
 
     /** Public for serialization purpose only. Use {@link OsVersionStatus#compute(Controller)} for an up-to-date status */
-    public OsVersionStatus(ImmutableMap<OsVersion, NodeVersions> versions) {
+    public OsVersionStatus(Map<OsVersion, List<NodeVersion>> versions) {
         this.versions = ImmutableMap.copyOf(Objects.requireNonNull(versions, "versions must be non-null"));
     }
 
     /** All known OS versions and their nodes */
-    public Map<OsVersion, NodeVersions> versions() {
+    public Map<OsVersion, List<NodeVersion>> versions() {
         return versions;
     }
 
@@ -44,8 +45,9 @@ public class OsVersionStatus {
     public List<NodeVersion> nodesIn(CloudName cloud) {
         return versions.entrySet().stream()
                        .filter(entry -> entry.getKey().cloud().equals(cloud))
-                       .flatMap(entry -> entry.getValue().asMap().values().stream())
-                       .collect(Collectors.toUnmodifiableList());
+                       .map(Map.Entry::getValue)
+                       .findFirst()
+                       .orElseGet(List::of);
     }
 
     /** Returns versions that exist in given cloud */
@@ -58,38 +60,30 @@ public class OsVersionStatus {
 
     /** Compute the current OS versions in this system. This is expensive and should be called infrequently */
     public static OsVersionStatus compute(Controller controller) {
-        var osVersions = new HashMap<OsVersion, List<NodeVersion>>();
+        Map<OsVersion, List<NodeVersion>> osVersions = new HashMap<>();
         controller.osVersionTargets().forEach(target -> osVersions.put(target.osVersion(), new ArrayList<>()));
 
         for (var application : SystemApplication.all()) {
             for (var zone : zonesToUpgrade(controller)) {
                 if (!application.shouldUpgradeOs()) continue;
-                var targetOsVersion = controller.serviceRegistry().configServer().nodeRepository()
-                                                .targetVersionsOf(zone.getVirtualId())
-                                                .osVersion(application.nodeType())
-                                                .orElse(Version.emptyVersion);
+                Version targetOsVersion = controller.serviceRegistry().configServer().nodeRepository()
+                                                    .targetVersionsOf(zone.getVirtualId())
+                                                    .osVersion(application.nodeType())
+                                                    .orElse(Version.emptyVersion);
 
                 for (var node : controller.serviceRegistry().configServer().nodeRepository().list(zone.getVirtualId(), application.id())) {
                     if (!OsUpgrader.canUpgrade(node)) continue;
-                    var suspendedAt = node.suspendedSince();
-                    var nodeVersion = new NodeVersion(node.hostname(), zone.getVirtualId(), node.currentOsVersion(),
-                                                      targetOsVersion, suspendedAt);
-                    var osVersion = new OsVersion(nodeVersion.currentVersion(), zone.getCloudName());
+                    Optional<Instant> suspendedAt = node.suspendedSince();
+                    NodeVersion nodeVersion = new NodeVersion(node.hostname(), zone.getVirtualId(), node.currentOsVersion(),
+                                                              targetOsVersion, suspendedAt);
+                    OsVersion osVersion = new OsVersion(nodeVersion.currentVersion(), zone.getCloudName());
                     osVersions.computeIfAbsent(osVersion, (k) -> new ArrayList<>())
                               .add(nodeVersion);
                 }
             }
         }
 
-        var newOsVersions = ImmutableMap.<OsVersion, NodeVersions>builder();
-        for (var osVersion : osVersions.entrySet()) {
-            var nodeVersions = ImmutableMap.<HostName, NodeVersion>builder();
-            for (var nodeVersion : osVersion.getValue()) {
-                nodeVersions.put(nodeVersion.hostname(), nodeVersion);
-            }
-            newOsVersions.put(osVersion.getKey(), new NodeVersions(nodeVersions.build()));
-        }
-        return new OsVersionStatus(newOsVersions.build());
+        return new OsVersionStatus(osVersions);
     }
 
     private static List<ZoneApi> zonesToUpgrade(Controller controller) {
diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/VersionStatus.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/VersionStatus.java
index c45cea29c33..beefaadb2a1 100644
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/VersionStatus.java
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/VersionStatus.java
@@ -12,7 +12,6 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
-import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -86,7 +85,7 @@ public class VersionStatus {
     /** Create a full, updated version status. This is expensive and should be done infrequently */
     public static VersionStatus compute(Controller controller) {
         VersionStatus versionStatus = controller.readVersionStatus();
-        NodeVersions systemApplicationVersions = findSystemApplicationVersions(controller, versionStatus);
+        List<NodeVersion> systemApplicationVersions = findSystemApplicationVersions(controller, versionStatus);
         Map<ControllerVersion, List<HostName>> controllerVersions = findControllerVersions(controller);
 
         Map<Version, List<HostName>> infrastructureVersions = new HashMap<>();
@@ -94,9 +93,9 @@ public class VersionStatus {
             infrastructureVersions.computeIfAbsent(kv.getKey().version(), (k) -> new ArrayList<>())
                                   .addAll(kv.getValue());
         }
-        for (var kv : systemApplicationVersions.asMap().entrySet()) {
-            infrastructureVersions.computeIfAbsent(kv.getValue().currentVersion(), (k) -> new ArrayList<>())
-                                  .add(kv.getKey());
+        for (var nodeVersion : systemApplicationVersions) {
+            infrastructureVersions.computeIfAbsent(nodeVersion.currentVersion(), (k) -> new ArrayList<>())
+                                  .add(nodeVersion.hostname());
         }
 
         // The system version is the oldest infrastructure version, if that version is newer than the current system
@@ -130,11 +129,14 @@ public class VersionStatus {
 
             try {
                 boolean isReleased = Collections.binarySearch(releasedVersions, statistics.version()) >= 0;
+                List<NodeVersion> nodeVersions = systemApplicationVersions.stream()
+                                                                          .filter(nodeVersion -> nodeVersion.currentVersion().equals(statistics.version()))
+                                                                          .collect(Collectors.toList());
                 VespaVersion vespaVersion = createVersion(statistics,
                                                           controllerVersions.keySet(),
                                                           systemVersion,
                                                           isReleased,
-                                                          systemApplicationVersions.matching(statistics.version()),
+                                                          nodeVersions,
                                                           controller,
                                                           versionStatus);
                 versions.add(vespaVersion);
@@ -149,8 +151,8 @@ public class VersionStatus {
         return new VersionStatus(versions);
     }
 
-    private static NodeVersions findSystemApplicationVersions(Controller controller, VersionStatus versionStatus) {
-        var nodeVersions = new LinkedHashMap<HostName, NodeVersion>();
+    private static List<NodeVersion> findSystemApplicationVersions(Controller controller, VersionStatus versionStatus) {
+        List<NodeVersion> nodeVersions = new ArrayList<>();
         for (var zone : controller.zoneRegistry().zones().controllerUpgraded().zones()) {
             for (var application : SystemApplication.notController()) {
                 var nodes = controller.serviceRegistry().configServer().nodeRepository()
@@ -168,11 +170,11 @@ public class VersionStatus {
                     var version = configConverged ? node.currentVersion() : controller.systemVersion(versionStatus);
                     var nodeVersion = new NodeVersion(node.hostname(), zone.getId(), version, node.wantedVersion(),
                                                       node.suspendedSince());
-                    nodeVersions.put(nodeVersion.hostname(), nodeVersion);
+                    nodeVersions.add(nodeVersion);
                 }
             }
         }
-        return NodeVersions.copyOf(nodeVersions);
+        return nodeVersions;
     }
 
     private static Map<ControllerVersion, List<HostName>> findControllerVersions(Controller controller) {
@@ -194,7 +196,7 @@ public class VersionStatus {
                                               Set<ControllerVersion> controllerVersions,
                                               Version systemVersion,
                                               boolean isReleased,
-                                              NodeVersions nodeVersions,
+                                              List<NodeVersion> nodeVersions,
                                               Controller controller,
                                               VersionStatus versionStatus) {
         ControllerVersion latestVersion = controllerVersions.stream().max(Comparator.naturalOrder()).get();
diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/VespaVersion.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/VespaVersion.java
index 3510a4f78cd..d61e0e37fae 100644
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/VespaVersion.java
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/versions/VespaVersion.java
@@ -9,6 +9,7 @@ import com.yahoo.vespa.hosted.controller.application.InstanceList;
 
 import java.time.Instant;
 import java.time.ZoneOffset;
+import java.util.List;
 
 import static com.yahoo.config.application.api.DeploymentSpec.UpgradePolicy;
 
@@ -28,12 +29,12 @@ public class VespaVersion implements Comparable<VespaVersion> {
     private final boolean isControllerVersion;
     private final boolean isSystemVersion;
     private final boolean isReleased;
-    private final NodeVersions nodeVersions;
+    private final List<NodeVersion> nodeVersions;
     private final Confidence confidence;
 
     public VespaVersion(Version version, String releaseCommit, Instant committedAt,
                         boolean isControllerVersion, boolean isSystemVersion, boolean isReleased,
-                        NodeVersions nodeVersions,
+                        List<NodeVersion> nodeVersions,
                         Confidence confidence) {
         this.version = version;
         this.releaseCommit = releaseCommit;
@@ -104,7 +105,7 @@ public class VespaVersion implements Comparable<VespaVersion> {
     public boolean isReleased() { return isReleased; }
 
     /** Returns the versions of nodes allocated to system applications (across all zones) */
-    public NodeVersions nodeVersions() {
+    public List<NodeVersion> nodeVersions() {
         return nodeVersions;
     }
 
diff --git a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/maintenance/OsUpgraderTest.java b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/maintenance/OsUpgraderTest.java
index 664a1fdc83c..092f72274e5 100644
--- a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/maintenance/OsUpgraderTest.java
+++ b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/maintenance/OsUpgraderTest.java
@@ -235,7 +235,7 @@ public class OsUpgraderTest {
     private List<NodeVersion> nodesOn(Version version) {
         return tester.controller().osVersionStatus().versions().entrySet().stream()
                      .filter(entry -> entry.getKey().version().equals(version))
-                     .flatMap(entry -> entry.getValue().asMap().values().stream())
+                     .flatMap(entry -> entry.getValue().stream())
                      .collect(Collectors.toList());
     }
 
diff --git a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/maintenance/OsVersionStatusUpdaterTest.java b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/maintenance/OsVersionStatusUpdaterTest.java
index 95f6af06230..307540a9694 100644
--- a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/maintenance/OsVersionStatusUpdaterTest.java
+++ b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/maintenance/OsVersionStatusUpdaterTest.java
@@ -45,8 +45,8 @@ public class OsVersionStatusUpdaterTest {
 
         var osVersions = tester.controller().osVersionStatus().versions();
         assertEquals(2, osVersions.size());
-        assertFalse("All nodes on unknown version", osVersions.get(new OsVersion(Version.emptyVersion, cloud)).asMap().isEmpty());
-        assertTrue("No nodes on current target", osVersions.get(new OsVersion(version1, cloud)).asMap().isEmpty());
+        assertFalse("All nodes on unknown version", osVersions.get(new OsVersion(Version.emptyVersion, cloud)).isEmpty());
+        assertTrue("No nodes on current target", osVersions.get(new OsVersion(version1, cloud)).isEmpty());
     }
 
 }
diff --git a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/persistence/OsVersionStatusSerializerTest.java b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/persistence/OsVersionStatusSerializerTest.java
index efdf412ab77..cff845c9dbe 100644
--- a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/persistence/OsVersionStatusSerializerTest.java
+++ b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/persistence/OsVersionStatusSerializerTest.java
@@ -1,19 +1,19 @@
 // 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.controller.persistence;
 
-import com.google.common.collect.ImmutableMap;
 import com.yahoo.component.Version;
 import com.yahoo.config.provision.CloudName;
 import com.yahoo.config.provision.HostName;
 import com.yahoo.config.provision.zone.ZoneId;
 import com.yahoo.vespa.hosted.controller.versions.NodeVersion;
-import com.yahoo.vespa.hosted.controller.versions.NodeVersions;
 import com.yahoo.vespa.hosted.controller.versions.OsVersion;
 import com.yahoo.vespa.hosted.controller.versions.OsVersionStatus;
 import org.junit.Test;
 
 import java.time.Instant;
+import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.Optional;
 
 import static org.junit.Assert.assertEquals;
@@ -27,19 +27,19 @@ public class OsVersionStatusSerializerTest {
     public void serialization() {
         Version version1 = Version.fromString("7.1");
         Version version2 = Version.fromString("7.2");
-        var versions = ImmutableMap.<OsVersion, NodeVersions>builder();
+        Map<OsVersion, List<NodeVersion>> versions = new LinkedHashMap<>();
 
-        versions.put(new OsVersion(version1, CloudName.defaultName()), NodeVersions.copyOf(List.of(
+        versions.put(new OsVersion(version1, CloudName.defaultName()), List.of(
                 new NodeVersion(HostName.from("node1"), ZoneId.from("prod", "us-west"), version1, version2, Optional.of(Instant.ofEpochMilli(11))),
                 new NodeVersion(HostName.from("node2"), ZoneId.from("prod", "us-east"), version1, version2, Optional.of(Instant.ofEpochMilli(22)))
-        )));
-        versions.put(new OsVersion(version2, CloudName.defaultName()), NodeVersions.copyOf(List.of(
+        ));
+        versions.put(new OsVersion(version2, CloudName.defaultName()), List.of(
                 new NodeVersion(HostName.from("node3"), ZoneId.from("prod", "us-west"), version2, version2, Optional.of(Instant.ofEpochMilli(33))),
                 new NodeVersion(HostName.from("node4"), ZoneId.from("prod", "us-east"), version2, version2, Optional.of(Instant.ofEpochMilli(44)))
-        )));
+        ));
 
         OsVersionStatusSerializer serializer = new OsVersionStatusSerializer(new OsVersionSerializer(), new NodeVersionSerializer());
-        OsVersionStatus status = new OsVersionStatus(versions.build());
+        OsVersionStatus status = new OsVersionStatus(versions);
         OsVersionStatus serialized = serializer.fromSlime(serializer.toSlime(status));
         assertEquals(status.versions(), serialized.versions());
     }
diff --git a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/persistence/VersionStatusSerializerTest.java b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/persistence/VersionStatusSerializerTest.java
index 41d59239321..a8bc83ff2ac 100644
--- a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/persistence/VersionStatusSerializerTest.java
+++ b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/persistence/VersionStatusSerializerTest.java
@@ -5,7 +5,6 @@ import com.yahoo.component.Version;
 import com.yahoo.config.provision.HostName;
 import com.yahoo.config.provision.zone.ZoneId;
 import com.yahoo.vespa.hosted.controller.versions.NodeVersion;
-import com.yahoo.vespa.hosted.controller.versions.NodeVersions;
 import com.yahoo.vespa.hosted.controller.versions.VersionStatus;
 import com.yahoo.vespa.hosted.controller.versions.VespaVersion;
 import org.junit.Test;
@@ -53,12 +52,12 @@ public class VersionStatusSerializerTest {
 
     }
 
-    private static NodeVersions nodeVersions(Version version, Version wantedVersion, String... hostnames) {
+    private static List<NodeVersion> nodeVersions(Version version, Version wantedVersion, String... hostnames) {
         var nodeVersions = new ArrayList<NodeVersion>();
         for (var hostname : hostnames) {
             nodeVersions.add(new NodeVersion(HostName.from(hostname), ZoneId.from("prod", "us-north-1"), version, wantedVersion, Optional.empty()));
         }
-        return NodeVersions.copyOf(nodeVersions);
+        return nodeVersions;
     }
 
 }
diff --git a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/restapi/deployment/DeploymentApiTest.java b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/restapi/deployment/DeploymentApiTest.java
index 3d07b5d51d4..cd24ec170c5 100644
--- a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/restapi/deployment/DeploymentApiTest.java
+++ b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/restapi/deployment/DeploymentApiTest.java
@@ -13,7 +13,6 @@ import com.yahoo.vespa.hosted.controller.deployment.DeploymentTester;
 import com.yahoo.vespa.hosted.controller.restapi.ContainerTester;
 import com.yahoo.vespa.hosted.controller.restapi.ControllerContainerTest;
 import com.yahoo.vespa.hosted.controller.versions.NodeVersion;
-import com.yahoo.vespa.hosted.controller.versions.NodeVersions;
 import com.yahoo.vespa.hosted.controller.versions.VersionStatus;
 import com.yahoo.vespa.hosted.controller.versions.VespaVersion;
 import org.junit.Test;
@@ -86,8 +85,8 @@ public class DeploymentApiTest extends ControllerContainerTest {
                                            version.isControllerVersion(),
                                            version.isSystemVersion(),
                                            version.isReleased(),
-                                           NodeVersions.copyOf(List.of(new NodeVersion(HostName.from("config1.test"), ZoneId.defaultId(), version.versionNumber(), version.versionNumber(), Optional.empty()),
-                                                                       new NodeVersion(HostName.from("config2.test"), ZoneId.defaultId(), version.versionNumber(), version.versionNumber(), Optional.empty()))),
+                                           List.of(new NodeVersion(HostName.from("config1.test"), ZoneId.defaultId(), version.versionNumber(), version.versionNumber(), Optional.empty()),
+                                                   new NodeVersion(HostName.from("config2.test"), ZoneId.defaultId(), version.versionNumber(), version.versionNumber(), Optional.empty())),
                                            version.confidence()
                 );
             }