Try to undo parts of FasterXML#4214, resolves this issue, but requires something wrt original problem

Author: cowtowncoder

Diff for: src/main/java/com/fasterxml/jackson/databind/deser/BasicDeserializerFactory.java

@@ -813,8 +813,7 @@ public JsonDeserializer<?> createCollectionDeserializer(DeserializationContext c
             if (contentDeser == null) { // not defined by annotation
                 // One special type: EnumSet:
                 if (EnumSet.class.isAssignableFrom(collectionClass)) {
-                    deser = new EnumSetDeserializer(contentType, null,
-                            contentTypeDeser);
+                    deser = new EnumSetDeserializer(contentType, null, null);
                 }
             }
         }

Diff for: src/main/java/com/fasterxml/jackson/databind/deser/std/EnumSetDeserializer.java

@@ -32,17 +32,6 @@ public class EnumSetDeserializer
 
     protected JsonDeserializer<Enum<?>> _enumDeserializer;
 
-    /**
-     * If element instances have polymorphic type information, this
-     * is the type deserializer that can handle it.
-     *<p>
-     * NOTE: only added in 2.17 due to new {@code DefaultType} choices
-     * that allow polymorphic deserialization of {@code Enum} types.
-     *
-     * @since 2.17
-     */
-    protected final TypeDeserializer _valueTypeDeserializer;
-
     /**
      * Handler we need for dealing with nulls.
      *
@@ -74,11 +63,12 @@ public class EnumSetDeserializer
      */
 
     /**
-     * @since 2.17
+     * Main constructor for the deserializer.
+     *<p>
+     * NOTE: was temporarily deprecated in 2.17 - 2.18, restored in 2.19
      */
     @SuppressWarnings("unchecked" )
-    public EnumSetDeserializer(JavaType enumType, JsonDeserializer<?> deser,
-            TypeDeserializer valueTypeDeser)
+    public EnumSetDeserializer(JavaType enumType, JsonDeserializer<?> deser)
     {
         super(EnumSet.class);
         _enumType = enumType;
@@ -87,19 +77,19 @@ public EnumSetDeserializer(JavaType enumType, JsonDeserializer<?> deser,
             throw new IllegalArgumentException("Type "+enumType+" not Java Enum type");
         }
         _enumDeserializer = (JsonDeserializer<Enum<?>>) deser;
-        _valueTypeDeserializer = valueTypeDeser;
         _unwrapSingle = null;
         _nullProvider = null;
         _skipNullValues = false;
     }
 
     /**
-     * @deprecated Since 2.17
+     * @deprecated Since 2.19 (was added in 2.17)
      */
     @Deprecated
-    public EnumSetDeserializer(JavaType enumType, JsonDeserializer<?> deser)
+    public EnumSetDeserializer(JavaType enumType, JsonDeserializer<?> deser,
+            TypeDeserializer valueTypeDeser)
     {
-        this(enumType, deser, null);
+        this(enumType, deser);
     }
 
     /**
@@ -121,7 +111,6 @@ protected EnumSetDeserializer(EnumSetDeserializer base,
         super(base);
         _enumType = base._enumType;
         _enumDeserializer = (JsonDeserializer<Enum<?>>) deser;
-        _valueTypeDeserializer = base._valueTypeDeserializer;
         _nullProvider = nuller;
         _skipNullValues = NullsConstantProvider.isSkipper(nuller);
         _unwrapSingle = unwrapSingle;
@@ -135,29 +124,18 @@ public EnumSetDeserializer withDeserializer(JsonDeserializer<?> deser) {
     }
 
     /**
-     * @since 2.10.1
+     * @since 2.19
      */
     public EnumSetDeserializer withResolved(JsonDeserializer<?> deser,
-            TypeDeserializer valueTypeDeser,
             NullValueProvider nuller, Boolean unwrapSingle) {
         if ((Objects.equals(_unwrapSingle, unwrapSingle))
                 && (_enumDeserializer == deser)
-                && (_valueTypeDeserializer == valueTypeDeser)
                 && (_nullProvider == deser)) {
             return this;
         }
         return new EnumSetDeserializer(this, deser, nuller, unwrapSingle);
     }
 
-    /**
-     * @deprecated Since 2.17
-     */
-    @Deprecated
-    public EnumSetDeserializer withResolved(JsonDeserializer<?> deser,
-            NullValueProvider nuller, Boolean unwrapSingle) {
-        return withResolved(deser, _valueTypeDeserializer, nuller, unwrapSingle);
-    }
-
     /*
     /**********************************************************
     /* Basic metadata
@@ -171,9 +149,7 @@ public EnumSetDeserializer withResolved(JsonDeserializer<?> deser,
     @Override
     public boolean isCachable() {
         // One caveat: content deserializer should prevent caching
-        if ((_enumType.getValueHandler() != null)
-                // Another: polymorphic deserialization
-                || (_valueTypeDeserializer != null)) {
+        if (_enumType.getValueHandler() != null) {
             return false;
         }
         return true;
@@ -220,12 +196,7 @@ public JsonDeserializer<?> createContextual(DeserializationContext ctxt,
         } else { // if directly assigned, probably not yet contextual, so:
             deser = ctxt.handleSecondaryContextualization(deser, property, _enumType);
         }
-        // and finally, type deserializer needs context as well
-        TypeDeserializer valueTypeDeser = _valueTypeDeserializer;
-        if (valueTypeDeser != null) {
-            valueTypeDeser = valueTypeDeser.forProperty(property);
-        }
-        return withResolved(deser, valueTypeDeser,
+        return withResolved(deser,
                 findContentNullProvider(ctxt, property, deser), unwrapSingle);
     }
 
@@ -261,10 +232,8 @@ public EnumSet<?> deserialize(JsonParser p, DeserializationContext ctxt,
     protected final EnumSet<?> _deserialize(JsonParser p, DeserializationContext ctxt,
             EnumSet result) throws IOException
     {
-        JsonToken t;
-        final TypeDeserializer typeDeser = _valueTypeDeserializer;
-
         try {
+            JsonToken t;
             while ((t = p.nextToken()) != JsonToken.END_ARRAY) {
                 // What to do with nulls? Fail or ignore? Fail, for now (note: would fail if we
                 // passed it to EnumDeserializer, too, but in general nulls should never be passed
@@ -275,10 +244,8 @@ protected final EnumSet<?> _deserialize(JsonParser p, DeserializationContext ctx
                         continue;
                     }
                     value = (Enum<?>) _nullProvider.getNullValue(ctxt);
-                } else if (typeDeser == null) {
-                    value = _enumDeserializer.deserialize(p, ctxt);
                 } else {
-                    value = (Enum<?>) _enumDeserializer.deserializeWithType(p, ctxt, typeDeser);
+                    value = _enumDeserializer.deserialize(p, ctxt);
                 }
                 if (value != null) {
                     result.add(value);

Diff for: src/main/java/com/fasterxml/jackson/databind/ser/std/EnumSetSerializer.java

@@ -26,7 +26,8 @@ public EnumSetSerializer(EnumSetSerializer src,
 
     @Override
     public EnumSetSerializer _withValueTypeSerializer(TypeSerializer vts) {
-        return new EnumSetSerializer(this, _property, vts, _elementSerializer, _unwrapSingle);
+        // no typing for enum elements (always strongly typed), so don't change
+        return this;
     }
 
     @Override
@@ -47,7 +48,7 @@ public boolean hasSingleElement(EnumSet<? extends Enum<?>> value) {
     }
 
     @Override
-    public final void serialize(EnumSet<? extends Enum<?>> value, JsonGenerator gen,
+    public void serialize(EnumSet<? extends Enum<?>> value, JsonGenerator gen,
             SerializerProvider provider) throws IOException
     {
         final int len = value.size();
@@ -70,12 +71,6 @@ public void serializeContents(EnumSet<? extends Enum<?>> value, JsonGenerator ge
         throws IOException
     {
         gen.assignCurrentValue(value);
-        if (_valueTypeSerializer != null) {
-            // 16-Dec-2024, tatu: As per [databind#4849], need to support polymorphic
-            //   types for elements
-             _serializeTypedContents(value, gen, provider, _valueTypeSerializer);
-             return;
-        }
         JsonSerializer<Object> enumSer = _elementSerializer;
         // Need to dynamically find instance serializer; unfortunately
         // that seems to be the only way to figure out type (no accessors
@@ -87,17 +82,4 @@ public void serializeContents(EnumSet<? extends Enum<?>> value, JsonGenerator ge
             enumSer.serialize(en, gen, provider);
         }
     }
-
-    private void _serializeTypedContents(EnumSet<? extends Enum<?>> value, JsonGenerator gen,
-            SerializerProvider provider, TypeSerializer vts)
-        throws IOException
-    {
-        JsonSerializer<Object> enumSer = _elementSerializer;
-        for (Enum<?> en : value) {
-            if (enumSer == null) {
-                enumSer = provider.findContentValueSerializer(en.getDeclaringClass(), _property);
-            }
-            enumSer.serializeWithType(en, gen, provider, vts);
-        }
-    }
 }

Diff for: src/test/java/com/fasterxml/jackson/databind/tofix/EnumSetDeserializationWithDefaultTyping4849Test.java renamed to src/test/java/com/fasterxml/jackson/databind/deser/enums/EnumSetDeserializationWithDefaultTyping4849Test.java

@@ -1,4 +1,4 @@
-package com.fasterxml.jackson.databind.tofix;
+package com.fasterxml.jackson.databind.deser.enums;
 
 import java.util.EnumSet;
 

Diff for: src/test/java/com/fasterxml/jackson/databind/deser/enums/EnumSetPolymorphicDeser4214Test.java

@@ -39,13 +39,14 @@ public void testPolymorphicDeserialization4214() throws Exception
     {
         // Need to use Default Typing to trigger issue
         ObjectMapper mapper = jsonMapperBuilder()
-                .activateDefaultTyping(BasicPolymorphicTypeValidator.builder().allowIfBaseType(Object.class).build(),
+                .activateDefaultTyping(BasicPolymorphicTypeValidator.builder()
+                        .allowIfBaseType(Object.class).build(),
                         DefaultTyping.NON_FINAL_AND_ENUMS)
                 .build();
 
         EnumSetHolder enumSetHolder = new EnumSetHolder();
         enumSetHolder.enumSet = EnumSet.allOf(MyEnum.class);
-        String json = mapper.writeValueAsString(enumSetHolder);
+        String json = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(enumSetHolder);
         EnumSetHolder result = mapper.readValue(json, EnumSetHolder.class);
         assertEquals(result, enumSetHolder);
     }