chore: address comments

benchmark/src/main/resources/benchmark.xsd

@@ -317,7 +317,7 @@
         <xs:sequence>
 
 
-          <xs:element maxOccurs="unbounded" minOccurs="0" name="enablePreviewFeatureList" nillable="true" type="tns:previewFeature"/>
+          <xs:element maxOccurs="unbounded" minOccurs="0" name="enablePreviewFeature" type="tns:previewFeature"/>
 
 
           <xs:element minOccurs="0" name="environmentMode" type="tns:environmentMode"/>

core/src/build/revapi-differences.json

@@ -89,7 +89,7 @@
           "annotationType": "jakarta.xml.bind.annotation.XmlType",
           "attribute": "propOrder",
           "oldValue": "{\"environmentMode\", \"daemon\", \"randomType\", \"randomSeed\", \"randomFactoryClass\", \"moveThreadCount\", \"moveThreadBufferSize\", \"threadFactoryClass\", \"monitoringConfig\", \"solutionClass\", \"entityClassList\", \"domainAccessType\", \"scoreDirectorFactoryConfig\", \"terminationConfig\", \"phaseConfigList\"}",
-          "newValue": "{\"enablePreviewFeatureList\", \"environmentMode\", \"daemon\", \"randomType\", \"randomSeed\", \"randomFactoryClass\", \"moveThreadCount\", \"moveThreadBufferSize\", \"threadFactoryClass\", \"monitoringConfig\", \"solutionClass\", \"entityClassList\", \"domainAccessType\", \"scoreDirectorFactoryConfig\", \"terminationConfig\", \"nearbyDistanceMeterClass\", \"phaseConfigList\"}",
+          "newValue": "{\"enablePreviewFeatureSet\", \"environmentMode\", \"daemon\", \"randomType\", \"randomSeed\", \"randomFactoryClass\", \"moveThreadCount\", \"moveThreadBufferSize\", \"threadFactoryClass\", \"monitoringConfig\", \"solutionClass\", \"entityClassList\", \"domainAccessType\", \"scoreDirectorFactoryConfig\", \"terminationConfig\", \"nearbyDistanceMeterClass\", \"phaseConfigList\"}",
           "justification": "Enable features preview config"
         }
       ]

core/src/main/java/ai/timefold/solver/core/config/solver/SolverConfig.java

@@ -10,11 +10,12 @@
 import java.io.UnsupportedEncodingException;
 import java.nio.charset.StandardCharsets;
 import java.time.Duration;
-import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.EnumSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.Set;
 import java.util.concurrent.ThreadFactory;
 import java.util.function.Consumer;
 
@@ -61,7 +62,7 @@
  */
 @XmlRootElement(name = SolverConfig.XML_ELEMENT_NAME)
 @XmlType(name = SolverConfig.XML_TYPE_NAME, propOrder = {
-        "enablePreviewFeatureList",
+        "enablePreviewFeatureSet",
         "environmentMode",
         "daemon",
         "randomType",
@@ -211,8 +212,8 @@ public class SolverConfig extends AbstractConfig<SolverConfig> {
 
     // Warning: all fields are null (and not defaulted) because they can be inherited
     // and also because the input config file should match the output config file
-
-    protected List<PreviewFeature> enablePreviewFeatureList = null;
+    @XmlElement(name = "enablePreviewFeature")
+    protected Set<PreviewFeature> enablePreviewFeatureSet = null;
     protected EnvironmentMode environmentMode = null;
     protected Boolean daemon = null;
     protected RandomType randomType = null;
@@ -287,12 +288,12 @@ public void setClassLoader(@Nullable ClassLoader classLoader) {
         this.classLoader = classLoader;
     }
 
-    public @Nullable List<PreviewFeature> getEnablePreviewFeatureList() {
-        return enablePreviewFeatureList;
+    public @Nullable Set<PreviewFeature> getEnablePreviewFeatureSet() {
+        return enablePreviewFeatureSet;
     }
 
-    public void setEnablePreviewFeatureList(@Nullable List<PreviewFeature> enablePreviewFeatureList) {
-        this.enablePreviewFeatureList = enablePreviewFeatureList;
+    public void setEnablePreviewFeatureSet(@Nullable Set<PreviewFeature> enablePreviewFeatureSet) {
+        this.enablePreviewFeatureSet = enablePreviewFeatureSet;
     }
 
     public @Nullable EnvironmentMode getEnvironmentMode() {
@@ -443,11 +444,8 @@ public void setMonitoringConfig(@Nullable MonitoringConfig monitoringConfig) {
     // With methods
     // ************************************************************************
 
-    public @NonNull SolverConfig withPreviewFeature(@NonNull PreviewFeature previewFeature) {
-        if (enablePreviewFeatureList == null) {
-            enablePreviewFeatureList = new ArrayList<>();
-        }
-        enablePreviewFeatureList.add(previewFeature);
+    public @NonNull SolverConfig withPreviewFeature(@NonNull PreviewFeature... previewFeature) {
+        enablePreviewFeatureSet = EnumSet.copyOf(Arrays.asList(previewFeature));
         return this;
     }
 
@@ -667,8 +665,8 @@ public void offerRandomSeedFromSubSingleIndex(long subSingleIndex) {
     @Override
     public @NonNull SolverConfig inherit(@NonNull SolverConfig inheritedConfig) {
         classLoader = ConfigUtils.inheritOverwritableProperty(classLoader, inheritedConfig.getClassLoader());
-        enablePreviewFeatureList = ConfigUtils.inheritMergeableListProperty(enablePreviewFeatureList,
-                inheritedConfig.getEnablePreviewFeatureList());
+        enablePreviewFeatureSet = ConfigUtils.inheritMergeableEnumSetProperty(enablePreviewFeatureSet,
+                inheritedConfig.getEnablePreviewFeatureSet());
         environmentMode = ConfigUtils.inheritOverwritableProperty(environmentMode, inheritedConfig.getEnvironmentMode());
         daemon = ConfigUtils.inheritOverwritableProperty(daemon, inheritedConfig.getDaemon());
         randomType = ConfigUtils.inheritOverwritableProperty(randomType, inheritedConfig.getRandomType());

core/src/main/java/ai/timefold/solver/core/config/util/ConfigUtils.java

@@ -17,6 +17,7 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.EnumSet;
 import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
 import java.util.List;
@@ -211,6 +212,19 @@ public static void applyCustomProperties(@NonNull Object bean, @NonNull String b
         }
     }
 
+    public static <E extends Enum<E>> @Nullable Set<E> inheritMergeableEnumSetProperty(@Nullable Set<E> originalSet,
+            @Nullable Set<E> inheritedSet) {
+        if (inheritedSet == null) {
+            return originalSet;
+        } else if (originalSet == null) {
+            return EnumSet.copyOf(inheritedSet);
+        } else {
+            var newSet = EnumSet.copyOf(originalSet);
+            newSet.addAll(inheritedSet);
+            return newSet;
+        }
+    }
+
     public static <T> @Nullable List<T> inheritUniqueMergeableListProperty(@Nullable List<T> originalList,
             @Nullable List<T> inheritedList) {
         if (inheritedList == null) {

core/src/main/java/ai/timefold/solver/core/impl/heuristic/HeuristicConfigPolicy.java

@@ -1,9 +1,9 @@
 package ai.timefold.solver.core.impl.heuristic;
 
 import java.util.HashMap;
-import java.util.List;
 import java.util.Map;
 import java.util.Random;
+import java.util.Set;
 import java.util.concurrent.ThreadFactory;
 
 import ai.timefold.solver.core.config.heuristic.selector.entity.EntitySorterManner;
@@ -27,7 +27,7 @@
 
 public class HeuristicConfigPolicy<Solution_> {
 
-    private final List<PreviewFeature> previewFeatureList;
+    private final Set<PreviewFeature> previewFeatureList;
     private final EnvironmentMode environmentMode;
     private final String logIndentation;
     private final Integer moveThreadCount;
@@ -132,8 +132,17 @@ public Random getRandom() {
     // ************************************************************************
 
     public Builder<Solution_> cloneBuilder() {
-        return new Builder<>(previewFeatureList, environmentMode, moveThreadCount, moveThreadBufferSize, threadFactoryClass,
-                nearbyDistanceMeterClass, random, initializingScoreTrend, solutionDescriptor, classInstanceCache)
+        return new Builder<Solution_>()
+                .withPreviewFeatureList(previewFeatureList)
+                .withEnvironmentMode(environmentMode)
+                .withMoveThreadCount(moveThreadCount)
+                .withMoveThreadBufferSize(moveThreadBufferSize)
+                .withThreadFactoryClass(threadFactoryClass)
+                .withNearbyDistanceMeterClass(nearbyDistanceMeterClass)
+                .withRandom(random)
+                .withInitializingScoreTrend(initializingScoreTrend)
+                .withSolutionDescriptor(solutionDescriptor)
+                .withClassInstanceCache(classInstanceCache)
                 .withLogIndentation(logIndentation);
     }
 
@@ -225,14 +234,14 @@ public String toString() {
 
     public static class Builder<Solution_> {
 
-        private final List<PreviewFeature> previewFeatureList;
-        private final EnvironmentMode environmentMode;
-        private final Integer moveThreadCount;
-        private final Integer moveThreadBufferSize;
-        private final Class<? extends ThreadFactory> threadFactoryClass;
-        private final InitializingScoreTrend initializingScoreTrend;
-        private final SolutionDescriptor<Solution_> solutionDescriptor;
-        private final ClassInstanceCache classInstanceCache;
+        private Set<PreviewFeature> previewFeatureList;
+        private EnvironmentMode environmentMode;
+        private Integer moveThreadCount;
+        private Integer moveThreadBufferSize;
+        private Class<? extends ThreadFactory> threadFactoryClass;
+        private InitializingScoreTrend initializingScoreTrend;
+        private SolutionDescriptor<Solution_> solutionDescriptor;
+        private ClassInstanceCache classInstanceCache;
 
         private String logIndentation = "";
 
@@ -243,24 +252,58 @@ public static class Builder<Solution_> {
         private boolean initializedChainedValueFilterEnabled = false;
         private boolean unassignedValuesAllowed = false;
 
-        private final Class<? extends NearbyDistanceMeter<?, ?>> nearbyDistanceMeterClass;
-        private final Random random;
+        private Class<? extends NearbyDistanceMeter<?, ?>> nearbyDistanceMeterClass;
+        private Random random;
 
-        public Builder(List<PreviewFeature> previewFeatureList, EnvironmentMode environmentMode, Integer moveThreadCount,
-                Integer moveThreadBufferSize, Class<? extends ThreadFactory> threadFactoryClass,
-                Class<? extends NearbyDistanceMeter<?, ?>> nearbyDistanceMeterClass, Random random,
-                InitializingScoreTrend initializingScoreTrend, SolutionDescriptor<Solution_> solutionDescriptor,
-                ClassInstanceCache classInstanceCache) {
+        public Builder<Solution_> withPreviewFeatureList(Set<PreviewFeature> previewFeatureList) {
             this.previewFeatureList = previewFeatureList;
+            return this;
+        }
+
+        public Builder<Solution_> withEnvironmentMode(EnvironmentMode environmentMode) {
             this.environmentMode = environmentMode;
+            return this;
+        }
+
+        public Builder<Solution_> withMoveThreadCount(Integer moveThreadCount) {
             this.moveThreadCount = moveThreadCount;
+            return this;
+        }
+
+        public Builder<Solution_> withMoveThreadBufferSize(Integer moveThreadBufferSize) {
             this.moveThreadBufferSize = moveThreadBufferSize;
+            return this;
+        }
+
+        public Builder<Solution_> withThreadFactoryClass(Class<? extends ThreadFactory> threadFactoryClass) {
             this.threadFactoryClass = threadFactoryClass;
+            return this;
+        }
+
+        public Builder<Solution_>
+                withNearbyDistanceMeterClass(Class<? extends NearbyDistanceMeter<?, ?>> nearbyDistanceMeterClass) {
             this.nearbyDistanceMeterClass = nearbyDistanceMeterClass;
+            return this;
+        }
+
+        public Builder<Solution_> withRandom(Random random) {
             this.random = random;
+            return this;
+        }
+
+        public Builder<Solution_> withInitializingScoreTrend(InitializingScoreTrend initializingScoreTrend) {
             this.initializingScoreTrend = initializingScoreTrend;
+            return this;
+        }
+
+        public Builder<Solution_> withSolutionDescriptor(SolutionDescriptor<Solution_> solutionDescriptor) {
             this.solutionDescriptor = solutionDescriptor;
+            return this;
+        }
+
+        public Builder<Solution_> withClassInstanceCache(ClassInstanceCache classInstanceCache) {
             this.classInstanceCache = classInstanceCache;
+            return this;
         }
 
         public Builder<Solution_> withLogIndentation(String logIndentation) {

core/src/main/java/ai/timefold/solver/core/impl/localsearch/decider/acceptor/AcceptorFactory.java

@@ -226,7 +226,7 @@ private Optional<LateAcceptanceAcceptor<Solution_>> buildLateAcceptanceAcceptor(
         return Optional.empty();
     }
 
-    private Optional<LateAcceptanceAcceptor<Solution_>>
+    private Optional<DiversifiedLateAcceptanceAcceptor<Solution_>>
             buildDiversifiedLateAcceptanceAcceptor(HeuristicConfigPolicy<Solution_> configPolicy) {
         if (acceptorTypeListsContainsAcceptorType(AcceptorType.DIVERSIFIED_LATE_ACCEPTANCE)) {
             configPolicy.ensurePreviewFeature(PreviewFeature.DIVERSIFIED_LATE_ACCEPTANCE);