Merge branch '2.16'

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -65,6 +65,8 @@ Project: jackson-databind
  (fix contributed by Joo-Hyuk K)
 #4082: `ClassUtil` fails with `java.lang.reflect.InaccessibleObjectException`
   trying to setAccessible on `OptionalInt` with JDK 17+
+#4090: Support sequenced collections (JDK 21)S
+ (contributed by @pjfanning)
 
 2.15.3 (not yet released)
 

src/main/java/tools/jackson/databind/deser/BasicDeserializerFactory.java

@@ -2359,6 +2359,10 @@ protected static class ContainerDefaultMappings {
             fallbacks.put(Deque.class.getName(), LinkedList.class);
             fallbacks.put(NavigableSet.class.getName(), TreeSet.class);
 
+            // Sequenced types added in JDK21
+            fallbacks.put("java.util.SequencedCollection", DEFAULT_LIST);
+            fallbacks.put("java.util.SequencedSet", LinkedHashSet.class);
+
             _collectionFallbacks = fallbacks;
         }
 
@@ -2379,6 +2383,9 @@ protected static class ContainerDefaultMappings {
             fallbacks.put(java.util.concurrent.ConcurrentNavigableMap.class.getName(),
                     java.util.concurrent.ConcurrentSkipListMap.class);
 
+            // Sequenced types added in JDK21
+            fallbacks.put("java.util.SequencedMap", LinkedHashMap.class);
+
             _mapFallbacks = fallbacks;
         }
 

src/test-jdk21/java/com/fasterxml/jackson/databind/jdk21/Java21CollectionsTest.java

@@ -0,0 +1,51 @@
+package com.fasterxml.jackson.databind.jdk21;
+
+import java.util.*;
+
+import com.fasterxml.jackson.databind.BaseMapTest;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.json.JsonMapper;
+
+public class Java21CollectionsTest extends BaseMapTest
+{
+    // [databind#4089]
+    record SequencedCollections(
+            SequencedCollection<String> sequencedCollection,
+            SequencedSet<String> sequencedSet,
+            SequencedMap<String, Integer> sequencedMap) {
+    }
+
+    public void testSequencedCollectionTypesDeserialize() throws Exception {
+        String json = """
+                {
+                    "sequencedCollection": ["A", "B"],
+                    "sequencedSet": ["C", "D"],
+                    "sequencedMap": {"A": 1, "B": 2}
+                }
+                """;
+
+        ObjectMapper objectMapper = JsonMapper.builder().build();
+        SequencedCollections value = objectMapper.readValue(json, SequencedCollections.class);
+        assertEquals(ArrayList.class, value.sequencedCollection.getClass());
+        assertEquals(LinkedHashSet.class, value.sequencedSet.getClass());
+        assertEquals(LinkedHashMap.class, value.sequencedMap.getClass());
+    }
+
+    public void testSequencedCollectionTypesRoundTrip() throws Exception {
+        ArrayList<String> arrayList = new ArrayList<>();
+        arrayList.add("A");
+        arrayList.add("B");
+        LinkedHashSet<String> linkedHashSet = new LinkedHashSet<>();
+        linkedHashSet.add("C");
+        linkedHashSet.add("D");
+        LinkedHashMap<String, Integer> linkedHashMap = new LinkedHashMap<>();
+        linkedHashMap.put("A", 1);
+        linkedHashMap.put("B", 2);
+        SequencedCollections input = new SequencedCollections(arrayList, linkedHashSet, linkedHashMap);
+
+        ObjectMapper objectMapper = JsonMapper.builder().build();
+        String json = objectMapper.writeValueAsString(input);
+        SequencedCollections value = objectMapper.readValue(json, SequencedCollections.class);
+        assertEquals(input, value);
+    }
+}