HV-2127 Use ImmutableCollections (List.of/Set.of/Map.of) instead of Collections.unmodifiableXxx

Signed-off-by: marko-bekhta <[email protected]>

Author: marko-bekhta

engine/src/main/java/org/hibernate/validator/internal/constraintvalidators/hv/UniqueElementsValidator.java

@@ -7,6 +7,7 @@
 import static java.util.stream.Collectors.toList;
 
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 import java.util.stream.Collectors;
@@ -53,7 +54,7 @@ public boolean isValid(Collection collection, ConstraintValidatorContext constra
 		if ( constraintValidatorContext instanceof HibernateConstraintValidatorContext ) {
 			constraintValidatorContext.unwrap( HibernateConstraintValidatorContext.class )
 					.addMessageParameter( "duplicates", duplicates.stream().map( String::valueOf ).collect( Collectors.joining( ", " ) ) )
-					.withDynamicPayload( CollectionHelper.toImmutableList( duplicates ) );
+					.withDynamicPayload( Collections.unmodifiableList( duplicates ) );
 		}
 
 		return false;

engine/src/main/java/org/hibernate/validator/internal/util/CollectionHelper.java

@@ -7,14 +7,12 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
-import java.util.Map.Entry;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
@@ -96,37 +94,15 @@ public static <T> Set<T> asSet(T... ts) {
 	}
 
 	public static <T> List<T> toImmutableList(List<? extends T> list) {
-		switch ( list.size() ) {
-			case 0:
-				return Collections.emptyList();
-			case 1:
-				return Collections.singletonList( list.get( 0 ) );
-			default:
-				return Collections.unmodifiableList( list );
-		}
+		return List.copyOf( list );
 	}
 
 	public static <T> Set<T> toImmutableSet(Set<? extends T> set) {
-		switch ( set.size() ) {
-			case 0:
-				return Collections.emptySet();
-			case 1:
-				return Collections.singleton( set.iterator().next() );
-			default:
-				return Collections.unmodifiableSet( set );
-		}
+		return Set.copyOf( set );
 	}
 
 	public static <K, V> Map<K, V> toImmutableMap(Map<K, V> map) {
-		switch ( map.size() ) {
-			case 0:
-				return Collections.emptyMap();
-			case 1:
-				Entry<K, V> entry = map.entrySet().iterator().next();
-				return Collections.singletonMap( entry.getKey(), entry.getValue() );
-			default:
-				return Collections.unmodifiableMap( map );
-		}
+		return Map.copyOf( map );
 	}
 
 	/**