Add 'model' config type

22 files changed, 298 insertions, 22 deletions

diff --git a/config-lib/abi-spec.json b/config-lib/abi-spec.json
index 45290714777..19dfd8535ae 100644
--- a/config-lib/abi-spec.json
+++ b/config-lib/abi-spec.json
@@ -272,7 +272,8 @@
       "public static java.util.Map asNodeMap(java.util.Map, com.yahoo.config.LeafNode)",
       "public static java.util.Map asFileNodeMap(java.util.Map)",
       "public static java.util.Map asPathNodeMap(java.util.Map)",
-      "public static java.util.Map asUrlNodeMap(java.util.Map)"
+      "public static java.util.Map asUrlNodeMap(java.util.Map)",
+      "public static java.util.Map asModelNodeMap(java.util.Map)"
     ],
     "fields": []
   },
@@ -287,7 +288,8 @@
       "public java.util.List asList()",
       "public static com.yahoo.config.LeafNodeVector createFileNodeVector(java.util.Collection)",
       "public static com.yahoo.config.LeafNodeVector createPathNodeVector(java.util.Collection)",
-      "public static com.yahoo.config.LeafNodeVector createUrlNodeVector(java.util.Collection)"
+      "public static com.yahoo.config.LeafNodeVector createUrlNodeVector(java.util.Collection)",
+      "public static com.yahoo.config.LeafNodeVector createModelNodeVector(java.util.Collection)"
     ],
     "fields": []
   },
@@ -308,6 +310,51 @@
     ],
     "fields": []
   },
+  "com.yahoo.config.ModelNode": {
+    "superClass": "com.yahoo.config.LeafNode",
+    "interfaces": [],
+    "attributes": [
+      "public"
+    ],
+    "methods": [
+      "public void <init>()",
+      "public void <init>(com.yahoo.config.ModelReference)",
+      "public com.yahoo.config.ModelReference value()",
+      "public java.lang.String getValue()",
+      "public java.lang.String toString()",
+      "protected boolean doSetValue(java.lang.String)",
+      "public com.yahoo.config.ModelReference getModelReference()",
+      "public static java.util.List toModelReferences(java.util.List)",
+      "public static java.util.Map toModelReferenceMap(java.util.Map)",
+      "public bridge synthetic java.lang.Object value()"
+    ],
+    "fields": []
+  },
+  "com.yahoo.config.ModelReference": {
+    "superClass": "java.lang.Object",
+    "interfaces": [],
+    "attributes": [
+      "public"
+    ],
+    "methods": [
+      "public void <init>(java.util.Optional, java.util.Optional, java.util.Optional)",
+      "public java.util.Optional modelId()",
+      "public java.util.Optional url()",
+      "public java.util.Optional path()",
+      "public com.yahoo.config.ModelReference withModelId(java.util.Optional)",
+      "public com.yahoo.config.ModelReference withUrl(java.util.Optional)",
+      "public com.yahoo.config.ModelReference withPath(java.util.Optional)",
+      "public java.lang.String value()",
+      "public boolean equals(java.lang.Object)",
+      "public int hashCode()",
+      "public java.lang.String toString()",
+      "public static com.yahoo.config.ModelReference fromModelId(java.lang.String)",
+      "public static com.yahoo.config.ModelReference fromUrl(java.lang.String)",
+      "public static com.yahoo.config.ModelReference fromPath(java.lang.String)",
+      "public static com.yahoo.config.ModelReference valueOf(java.lang.String)"
+    ],
+    "fields": []
+  },
   "com.yahoo.config.Node": {
     "superClass": "java.lang.Object",
     "interfaces": [],
diff --git a/config-lib/src/main/java/com/yahoo/config/FileNode.java b/config-lib/src/main/java/com/yahoo/config/FileNode.java
index e6a4af6f439..a7c1ebb1488 100644
--- a/config-lib/src/main/java/com/yahoo/config/FileNode.java
+++ b/config-lib/src/main/java/com/yahoo/config/FileNode.java
@@ -1,8 +1,6 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.config;
 
-import java.nio.file.Path;
-
 /**
  * Represents a 'file' in a {@link ConfigInstance}, usually a filename.
  *
@@ -16,8 +14,6 @@ public class FileNode extends LeafNode<FileReference> {
     public FileNode(String stringVal) {
         super(true);
         this.value = new FileReference(ReferenceNode.stripQuotes(stringVal));
-        if (Path.of(value.value()).normalize().startsWith(".."))
-            throw new IllegalArgumentException("path may not start with '..', but got: " + value.value());
     }
 
     public FileReference value() {
diff --git a/config-lib/src/main/java/com/yahoo/config/FileReference.java b/config-lib/src/main/java/com/yahoo/config/FileReference.java
index 686721e91ae..8b8434c8cc4 100755
--- a/config-lib/src/main/java/com/yahoo/config/FileReference.java
+++ b/config-lib/src/main/java/com/yahoo/config/FileReference.java
@@ -2,6 +2,7 @@
 package com.yahoo.config;
 
 import java.io.File;
+import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.LinkedHashMap;
@@ -19,6 +20,8 @@ public final class FileReference {
     private final String value;
 
     public FileReference(String value) {
+        if (Path.of(value).normalize().startsWith(".."))
+            throw new IllegalArgumentException("Path may not start with '..' but got '" + value + "'");
         this.value = Objects.requireNonNull(value);
     }
 
diff --git a/config-lib/src/main/java/com/yahoo/config/LeafNodeMaps.java b/config-lib/src/main/java/com/yahoo/config/LeafNodeMaps.java
index 9435c09803f..82663fa8bfd 100644
--- a/config-lib/src/main/java/com/yahoo/config/LeafNodeMaps.java
+++ b/config-lib/src/main/java/com/yahoo/config/LeafNodeMaps.java
@@ -8,7 +8,6 @@ import java.util.stream.Collectors;
 
 /**
  * @author gjoranv
- * @since 5.1.17
  */
 public class LeafNodeMaps {
 
@@ -68,4 +67,11 @@ public class LeafNodeMaps {
                     ));
     }
 
+    public static Map<String, ModelNode> asModelNodeMap(Map<String, ModelReference> modelReferenceMap) {
+        return Collections.unmodifiableMap(
+                modelReferenceMap.entrySet().stream().collect(
+                        Collectors.toMap(Map.Entry::getKey, e -> new ModelNode(e.getValue()))
+                ));
+    }
+
 }
diff --git a/config-lib/src/main/java/com/yahoo/config/LeafNodeVector.java b/config-lib/src/main/java/com/yahoo/config/LeafNodeVector.java
index 599385899e1..bdabc045e18 100644
--- a/config-lib/src/main/java/com/yahoo/config/LeafNodeVector.java
+++ b/config-lib/src/main/java/com/yahoo/config/LeafNodeVector.java
@@ -13,7 +13,6 @@ import java.util.List;
  * A vector of leaf nodes.
  *
  * @author gjoranv
- * @since 5.1.4
  */
 public class LeafNodeVector<REAL, NODE extends LeafNode<REAL>> extends NodeVector<NODE> {
 
@@ -79,5 +78,11 @@ public class LeafNodeVector<REAL, NODE extends LeafNode<REAL>> extends NodeVecto
         return new LeafNodeVector<>(files, new UrlNode());
     }
 
+    public static LeafNodeVector<ModelReference, ModelNode> createModelNodeVector(Collection<ModelReference> values) {
+        List<ModelReference> models = new ArrayList<>();
+        for (ModelReference modelReference : values)
+            models.add(modelReference);
+        return new LeafNodeVector<>(models, new ModelNode());
+    }
 
 }
diff --git a/config-lib/src/main/java/com/yahoo/config/ModelNode.java b/config-lib/src/main/java/com/yahoo/config/ModelNode.java
new file mode 100644
index 00000000000..775c4a12e82
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/ModelNode.java
@@ -0,0 +1,64 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Represents a 'model' in a {@link ConfigInstance}.
+ *
+ * @author bratseth
+ */
+public class ModelNode extends LeafNode<ModelReference> {
+
+    public ModelNode() {
+        this.value = null;
+    }
+
+    public ModelNode(ModelReference modelReference) {
+        super(true);
+        this.value = modelReference;
+    }
+
+    public ModelReference value() {
+        return value;
+    }
+
+    @Override
+    public String getValue() {
+        return value.toString();
+    }
+
+    @Override
+    public String toString() {
+        return (value == null) ? "(null)" : '"' + getValue() + '"';
+    }
+
+    @Override
+    protected boolean doSetValue(String stringVal) {
+        throw new UnsupportedOperationException();
+    }
+
+    public ModelReference getModelReference() {
+        return value;
+    }
+
+    public static List<ModelReference> toModelReferences(List<ModelNode> modelNodes) {
+        List<ModelReference> modelReferences = new ArrayList<>();
+        for (ModelNode modelNode : modelNodes)
+            modelReferences.add(modelNode.getModelReference());
+        return modelReferences;
+    }
+
+    public static Map<String, ModelReference> toModelReferenceMap(Map<String, ModelNode> nodeMap) {
+        Map<String, ModelReference> referenceMap = new LinkedHashMap<>();
+        for (var entry : nodeMap.entrySet()) {
+            referenceMap.put(entry.getKey(), entry.getValue().getModelReference());
+        }
+        return referenceMap;
+    }
+
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/ModelReference.java b/config-lib/src/main/java/com/yahoo/config/ModelReference.java
new file mode 100644
index 00000000000..c0b610e4df3
--- /dev/null
+++ b/config-lib/src/main/java/com/yahoo/config/ModelReference.java
@@ -0,0 +1,109 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import java.io.File;
+import java.util.Objects;
+import java.util.Optional;
+
+/**
+ * An immutable reference to a model.
+ * This is a file path when read by a client but is set in a config instance either as a
+ * path, url or id resolved to an url during deployment.
+ *
+ * @author bratseth
+ */
+public class ModelReference {
+
+    // At least one of these are set
+    private final Optional<String> modelId;
+    private final Optional<UrlReference> url;
+    private final Optional<FileReference> path;
+
+    public ModelReference(Optional<String> modelId,
+                          Optional<UrlReference> url,
+                          Optional<FileReference> path) {
+        if (modelId.isEmpty() && url.isEmpty() && path.isEmpty())
+            throw new IllegalArgumentException("A model reference must have either a model id, url or path");
+        this.modelId = modelId;
+        this.url = url;
+        this.path = path;
+    }
+
+    public Optional<String> modelId() { return modelId; }
+    public Optional<UrlReference> url() { return url; }
+    public Optional<FileReference> path() { return path; }
+
+    public ModelReference withModelId(Optional<String> modelId) {
+        return new ModelReference(modelId, url, path);
+    }
+
+    public ModelReference withUrl(Optional<UrlReference> url) {
+        return new ModelReference(modelId, url, path);
+    }
+
+    public ModelReference withPath(Optional<FileReference> path) {
+        return new ModelReference(modelId, url, path);
+    }
+
+    /** Returns the path to the file containing this model. */
+    public String value() {
+        if (url.isPresent() && new File(url.get().value()).exists())
+            return new File(url.get().value()).getAbsolutePath();
+        if (path.isPresent())
+            return path.get().value();
+        throw new IllegalStateException("No url or path is available");
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if ( ! (o instanceof ModelReference other)) return false;
+        if ( ! this.modelId.equals(other.modelId)) return false;
+        if ( ! this.url.equals(other.url)) return false;
+        if ( ! this.path.equals(other.path)) return false;
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(modelId, url, path);
+    }
+
+    /** Returns this on the format accepted by valueOf */
+    @Override
+    public String toString() {
+        return modelId.orElse("") + " " +
+               url.map(v -> v.value()).orElse("") + " " +
+               path.map(v -> v.value()).orElse("");
+    }
+
+    /** Creates a model reference having a model id only. */
+    public static ModelReference fromModelId(String modelId) {
+        return new ModelReference(Optional.of(modelId), Optional.empty(), Optional.empty());
+    }
+
+    /** Creates a model reference having a url only. */
+    public static ModelReference fromUrl(String url) {
+        return new ModelReference(Optional.empty(), Optional.of(new UrlReference(url)), Optional.empty());
+    }
+
+    /** Creates a model reference having a path only. */
+    public static ModelReference fromPath(String path) {
+        return new ModelReference(Optional.empty(), Optional.empty(), Optional.of(new FileReference(path)));
+    }
+
+    /**
+     * Creates a model reference from a three-part string on the form
+     * <code>modelId url path</code>
+     * Each of the elements are either a value not containing space, or empty represented by "".
+     */
+    public static ModelReference valueOf(String s) {
+        String[] parts = s.split(" ");
+        if (parts.length != 3)
+            throw new IllegalArgumentException("Expected a config with exactly three space-separated parts, but got '" + s + "'");
+        return new ModelReference(parts[0].equals("") ? Optional.empty() : Optional.of(parts[0]),
+                                  parts[1].equals("") ? Optional.empty() : Optional.of(new UrlReference(parts[1])),
+                                  parts[2].equals("") ? Optional.empty() : Optional.of(new FileReference(parts[2])));
+
+    }
+
+}
diff --git a/config-lib/src/main/java/com/yahoo/config/PathNode.java b/config-lib/src/main/java/com/yahoo/config/PathNode.java
index ea4c657af8c..b757e569ffe 100644
--- a/config-lib/src/main/java/com/yahoo/config/PathNode.java
+++ b/config-lib/src/main/java/com/yahoo/config/PathNode.java
@@ -1,7 +1,6 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.config;
 
-import java.io.File;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.LinkedHashMap;
diff --git a/config-lib/src/main/java/com/yahoo/config/UrlReference.java b/config-lib/src/main/java/com/yahoo/config/UrlReference.java
index 1adab8aaa53..d7a74165896 100755
--- a/config-lib/src/main/java/com/yahoo/config/UrlReference.java
+++ b/config-lib/src/main/java/com/yahoo/config/UrlReference.java
@@ -11,6 +11,7 @@ import java.util.Objects;
  */
 public final class UrlReference {
 
+    /** Either the url or, if downloaded, the absolute path to the downloaded file. */
     private final String value;
 
     public UrlReference(String value) {
diff --git a/config-lib/src/test/java/com/yahoo/config/BooleanNodeTest.java b/config-lib/src/test/java/com/yahoo/config/BooleanNodeTest.java
index 50d71ba50e9..4d6b39f3976 100644
--- a/config-lib/src/test/java/com/yahoo/config/BooleanNodeTest.java
+++ b/config-lib/src/test/java/com/yahoo/config/BooleanNodeTest.java
@@ -8,9 +8,9 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Ulf Lilleengen
- * @since 5.1
  */
 public class BooleanNodeTest {
+
     @Test
     void testSetValue() {
         BooleanNode n = new BooleanNode();
@@ -21,4 +21,5 @@ public class BooleanNodeTest {
         assertFalse(n.doSetValue("FALSEa"));
         assertFalse(n.doSetValue("aFALSE"));
     }
+
 }
diff --git a/config-lib/src/test/java/com/yahoo/config/ConfigInstanceBuilderTest.java b/config-lib/src/test/java/com/yahoo/config/ConfigInstanceBuilderTest.java
index f05baeff08c..d1cd7678911 100644
--- a/config-lib/src/test/java/com/yahoo/config/ConfigInstanceBuilderTest.java
+++ b/config-lib/src/test/java/com/yahoo/config/ConfigInstanceBuilderTest.java
@@ -15,6 +15,7 @@ import java.lang.reflect.Method;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Optional;
 
 import static com.yahoo.foo.StructtypesConfig.Simple.Gender.Enum.FEMALE;
 import static com.yahoo.test.FunctionTestConfig.BasicStruct;
@@ -34,10 +35,8 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author gjoranv
- * @since 5.1.11
  */
-public class ConfigInstanceBuilderTest
-{
+public class ConfigInstanceBuilderTest {
 
     @Test
     void struct_values_can_be_set_without_declaring_a_new_struct_builder() {
@@ -170,6 +169,9 @@ public class ConfigInstanceBuilderTest
                 fileVal("etc").
                 pathVal(FileReference.mockFileReferenceForUnitTesting(new File("pom.xml"))).
                 urlVal(new UrlReference("http://docs.vespa.ai")).
+                modelVal(new ModelReference(Optional.empty(),
+                                            Optional.empty(),
+                                            Optional.of(FileReference.mockFileReferenceForUnitTesting(new File("pom.xml"))))).
                 boolarr(false).
                 longarr(9223372036854775807L).
                 longarr(-9223372036854775808L).
@@ -408,4 +410,5 @@ public class ConfigInstanceBuilderTest
                 report.toString().contains("function-test.myStructMap{one} with value \n")
         );
     }
+
 }
diff --git a/config-lib/src/test/java/com/yahoo/config/ConfigInstanceEqualsTest.java b/config-lib/src/test/java/com/yahoo/config/ConfigInstanceEqualsTest.java
index 1584293a137..1a05c08d8f2 100644
--- a/config-lib/src/test/java/com/yahoo/config/ConfigInstanceEqualsTest.java
+++ b/config-lib/src/test/java/com/yahoo/config/ConfigInstanceEqualsTest.java
@@ -8,6 +8,7 @@ import org.junit.jupiter.api.Test;
 
 import java.io.File;
 import java.util.Arrays;
+import java.util.Optional;
 
 import static com.yahoo.test.FunctionTestConfig.BasicStruct;
 import static com.yahoo.test.FunctionTestConfig.Enum_val;
@@ -18,6 +19,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
 
 public class ConfigInstanceEqualsTest {
+
     FunctionTestConfig config1;
     FunctionTestConfig.Builder builder2;
     FunctionTestConfig config2;
@@ -130,6 +132,9 @@ public class ConfigInstanceEqualsTest {
                 fileVal("etc").
                 pathVal(FileReference.mockFileReferenceForUnitTesting(new File("pom.xml"))).
                 urlVal(new UrlReference("http://docs.vespa.ai")).
+                modelVal(new ModelReference(Optional.of("my-model-id"),
+                                            Optional.of(new UrlReference("http://docs.vespa.ai")),
+                                            Optional.empty())).
                 boolarr(false).
                 longarr(9223372036854775807L).
                 longarr(-9223372036854775808L).
@@ -140,6 +145,9 @@ public class ConfigInstanceEqualsTest {
                 refarr(Arrays.asList(":parent:", ":parent", "parent:")).  // test collection based setter
                 fileArr("bin").
                 urlArr(new UrlReference("http://docs.vespa.ai")).
+                modelArr(new ModelReference(Optional.empty(),
+                                            Optional.of(new UrlReference("http://docs.vespa.ai")),
+                                            Optional.of(FileReference.mockFileReferenceForUnitTesting(new File("pom.xml"))))).
 
                 basicStruct(new BasicStruct.Builder().
                         foo("basicFoo").
@@ -183,4 +191,5 @@ public class ConfigInstanceEqualsTest {
                                 b(-2)));
 
     }
+
 }
diff --git a/config-lib/src/test/java/com/yahoo/config/DoubleNodeTest.java b/config-lib/src/test/java/com/yahoo/config/DoubleNodeTest.java
index 475a33104b0..ae9894041f9 100644
--- a/config-lib/src/test/java/com/yahoo/config/DoubleNodeTest.java
+++ b/config-lib/src/test/java/com/yahoo/config/DoubleNodeTest.java
@@ -10,9 +10,9 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Ulf Lilleengen
- * @since 5.1
  */
 public class DoubleNodeTest {
+
     @Test
     void testSetValue() {
         DoubleNode n = new DoubleNode();
@@ -20,4 +20,5 @@ public class DoubleNodeTest {
         assertTrue(n.doSetValue("3.14"));
         assertEquals(3.14, n.value(), 0.001);
     }
+
 }
diff --git a/config-lib/src/test/java/com/yahoo/config/EnumNodeTest.java b/config-lib/src/test/java/com/yahoo/config/EnumNodeTest.java
index e7723409736..d53db9fa9c7 100644
--- a/config-lib/src/test/java/com/yahoo/config/EnumNodeTest.java
+++ b/config-lib/src/test/java/com/yahoo/config/EnumNodeTest.java
@@ -12,6 +12,7 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  * @author Ulf Lilleengen
  */
 public class EnumNodeTest {
+
     private static class MyNode extends EnumNode<MyNode.Enum> {
         public enum Enum { ONE, TWO }
         public final static Enum ONE = Enum.ONE;
@@ -39,4 +40,5 @@ public class EnumNodeTest {
         assertEquals("ONE", n.toString());
         assertFalse(n.doSetValue("THREE"));
     }
+
 }
diff --git a/config-lib/src/test/java/com/yahoo/config/FileNodeTest.java b/config-lib/src/test/java/com/yahoo/config/FileNodeTest.java
index 8bec9378f8f..49796c795a9 100644
--- a/config-lib/src/test/java/com/yahoo/config/FileNodeTest.java
+++ b/config-lib/src/test/java/com/yahoo/config/FileNodeTest.java
@@ -9,7 +9,6 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Ulf Lilleengen
- * @since 5.1
  */
 public class FileNodeTest {
 
@@ -23,7 +22,7 @@ public class FileNodeTest {
         assertEquals("foo.txt", n.value().value());
         assertEquals("\"foo.txt\"", n.toString());
 
-        assertEquals("path may not start with '..', but got: foo/../../boo",
+        assertEquals("Path may not start with '..' but got 'foo/../../boo'",
                 assertThrows(IllegalArgumentException.class, () -> new FileNode("foo/../../boo")).getMessage());
     }
 
diff --git a/config-lib/src/test/java/com/yahoo/config/IntegerNodeTest.java b/config-lib/src/test/java/com/yahoo/config/IntegerNodeTest.java
index a195a5f65fb..4081192d2e8 100644
--- a/config-lib/src/test/java/com/yahoo/config/IntegerNodeTest.java
+++ b/config-lib/src/test/java/com/yahoo/config/IntegerNodeTest.java
@@ -9,9 +9,9 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Ulf Lilleengen
- * @since 5.1
  */
 public class IntegerNodeTest {
+
     @Test
     void testSetValue() {
         IntegerNode n = new IntegerNode();
@@ -19,4 +19,5 @@ public class IntegerNodeTest {
         assertTrue(n.setValue("10"));
         assertEquals(10, n.value().intValue());
     }
+
 }
diff --git a/config-lib/src/test/java/com/yahoo/config/LongNodeTest.java b/config-lib/src/test/java/com/yahoo/config/LongNodeTest.java
index dc6d59bbc46..9e021edd3a8 100644
--- a/config-lib/src/test/java/com/yahoo/config/LongNodeTest.java
+++ b/config-lib/src/test/java/com/yahoo/config/LongNodeTest.java
@@ -9,9 +9,9 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Ulf Lilleengen
- * @since 5.1
  */
 public class LongNodeTest {
+
     @Test
     void testSetValue() {
         LongNode n = new LongNode();
@@ -19,4 +19,5 @@ public class LongNodeTest {
         assertTrue(n.setValue("10"));
         assertEquals(10L, n.value().longValue());
     }
+
 }
diff --git a/config-lib/src/test/java/com/yahoo/config/ModelNodeTest.java b/config-lib/src/test/java/com/yahoo/config/ModelNodeTest.java
new file mode 100644
index 00000000000..696e0722714
--- /dev/null
+++ b/config-lib/src/test/java/com/yahoo/config/ModelNodeTest.java
@@ -0,0 +1,29 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Optional;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * @author bratseth
+ */
+public class ModelNodeTest {
+
+    @Test
+    void testEmpty() {
+        assertEquals("(null)", new ModelNode().toString());
+    }
+
+    @Test
+    void testReference() {
+        var reference = new ModelReference(Optional.of("myModelId"),
+                                           Optional.of(new UrlReference("https://host:my/path")),
+                                           Optional.of(new FileReference("foo.txt")));
+        assertEquals("myModelId https://host:my/path foo.txt", reference.toString());
+        assertEquals(reference, ModelReference.valueOf(reference.toString()));
+    }
+
+}
diff --git a/config-lib/src/test/java/com/yahoo/config/NodeVectorTest.java b/config-lib/src/test/java/com/yahoo/config/NodeVectorTest.java
index e6b3b4b6a71..fb751931062 100644
--- a/config-lib/src/test/java/com/yahoo/config/NodeVectorTest.java
+++ b/config-lib/src/test/java/com/yahoo/config/NodeVectorTest.java
@@ -12,7 +12,6 @@ import static org.junit.jupiter.api.Assertions.assertThrows;
 
 /**
  * @author Ulf Lilleengen
- * @since 5.1
  */
 public class NodeVectorTest {
 
diff --git a/config-lib/src/test/java/com/yahoo/config/PathNodeTest.java b/config-lib/src/test/java/com/yahoo/config/PathNodeTest.java
index ad8f5e2e65f..622466d95a2 100644
--- a/config-lib/src/test/java/com/yahoo/config/PathNodeTest.java
+++ b/config-lib/src/test/java/com/yahoo/config/PathNodeTest.java
@@ -10,7 +10,6 @@ import static org.junit.jupiter.api.Assertions.assertThrows;
 
 /**
  * @author gjoranv
- * @since 5.1.28
  */
 public class PathNodeTest {
 
@@ -22,7 +21,7 @@ public class PathNodeTest {
         n = new PathNode(new FileReference("foo.txt"));
         assertEquals(new File("foo.txt").toPath(), n.value());
 
-        assertEquals("path may not start with '..', but got: foo/../../boo",
+        assertEquals("Path may not start with '..' but got 'foo/../../boo'",
                 assertThrows(IllegalArgumentException.class, () -> new PathNode(new FileReference("foo/../../boo"))).getMessage());
     }
 
diff --git a/config-lib/src/test/java/com/yahoo/config/StringNodeTest.java b/config-lib/src/test/java/com/yahoo/config/StringNodeTest.java
index d0baf8d1837..3470c96bbcc 100644
--- a/config-lib/src/test/java/com/yahoo/config/StringNodeTest.java
+++ b/config-lib/src/test/java/com/yahoo/config/StringNodeTest.java
@@ -8,7 +8,6 @@ import static org.junit.jupiter.api.Assertions.assertThrows;
 
 /**
  * @author hmusum
- * @since 5.1.7
  */
 public class StringNodeTest {
 
diff --git a/config-lib/src/test/resources/configdefinitions/test.function-test.def b/config-lib/src/test/resources/configdefinitions/test.function-test.def
index f6a997daf77..cdd4bf012d2 100644
--- a/config-lib/src/test/resources/configdefinitions/test.function-test.def
+++ b/config-lib/src/test/resources/configdefinitions/test.function-test.def
@@ -45,6 +45,7 @@ refwithdef reference default=":parent:" restart
 fileVal file restart
 pathVal path restart
 urlVal url
+modelVal model
 
 boolarr[] bool restart
 intarr[] int restart
@@ -56,6 +57,7 @@ refarr[] reference restart
 fileArr[] file restart
 pathArr[] path restart
 urlArr[] url
+modelArr[] model
 
 #This is a map of ints.
 intMap{} int restart
@@ -63,6 +65,7 @@ stringMap{} string restart
 filemap{} file restart
 pathMap{} path restart
 urlMap{} url
+modelMap{} model
 
 # A basic struct
 basicStruct.foo string default="basic" restart