fix: enable enum type metadata serialization with NON_FINAL_AND_ENUMS

[lukman48]

Description

Fixes issue #3306: RedisCache with GenericJacksonJsonRedisSerializer breaks when using enums.

Problem

When using GenericJacksonJsonRedisSerializer, enum values are always serialized without type metadata, even when DefaultTyping.NON_FINAL_AND_ENUMS is explicitly configured. This causes ClassCastException during deserialization.

Example

public enum Status {
    ACTIVE, INACTIVE
}

@Cacheable(cacheNames = "status")
public Status getStatus(String id) {
    return Status.ACTIVE;
}

When configured with:

GenericJacksonJsonRedisSerializer.create(b -> {
    b.customize(mb -> mb.activateDefaultTypingAsProperty(
        ptv,
        DefaultTyping.NON_FINAL_AND_ENUMS,
        "@class"
    ));
});

Expected: Enum cached with type metadata, deserializes correctly to Status enum
Actual: Throws ClassCastException: class java.lang.String cannot be cast to class Status

Root Cause

TypeResolverBuilder.useForType() unconditionally excludes enum types regardless of the DefaultTyping setting:

if (javaType.isEnumType() || ClassUtils.isPrimitiveOrWrapper(javaType.getRawClass())) {
    return false;  // Always excluded
}

This doesn't account for DefaultTyping.NON_FINAL_AND_ENUMS which explicitly requests enum type metadata.

Solution

1. Store DefaultTyping in TypeResolverBuilder - Add a field to preserve the typing configuration
2. Update useForType() logic - Check the DefaultTyping setting before excluding enums:
   • Return true for enums when DefaultTyping == NON_FINAL_AND_ENUMS
   • Return false for other settings (maintains backward compatibility)
3. Preserve existing behavior - Kotlin support and other logic unchanged

Implementation Details

Changes Made

File: GenericJacksonJsonRedisSerializer.java

1. Add defaultTyping field to TypeResolverBuilder
2. Initialize in all three constructors
3. Update useForType() to respect the configuration:

if (javaType.isEnumType()) {
    // Respect DefaultTyping.NON_FINAL_AND_ENUMS for enum types
    return defaultTyping == DefaultTyping.NON_FINAL_AND_ENUMS;
}

Test Coverage

Added three test cases in GenericJacksonJsonRedisSerializerUnitTests:

1. shouldSerializeEnumWithTypeMetadataWhenUsingNonFinalAndEnumsTyping

   • Verifies enums include type metadata when explicitly requested
   • Confirms correct deserialization to Enum type

2. shouldDeserializeEnumWithoutTypeMetadataUsingNonFinalTyping

   • Verifies backward compatibility
   • Confirms enums excluded with NON_FINAL

3. shouldHandleEnumWithUnsafeDefaultTyping_StillConvertsToStringDueToLegacyBehavior

   • Documents original bug (enums deserialize as strings with unsafe typing)
   • Shows our fix enables proper handling when configured correctly

Test Results: All 30 existing tests pass ✅

Backward Compatibility

✅ No breaking changes:

• Enums still excluded by default (NON_FINAL, OBJECT_AND_NON_FINAL, etc.)
• Only included when explicitly requested via NON_FINAL_AND_ENUMS
• No API changes
• All existing tests pass
• Kotlin support preserved

Validation

mvn clean test -Dtest=GenericJacksonJsonRedisSerializerUnitTests
# Results: Tests run: 30, Failures: 0, Errors: 0, Skipped: 0
# BUILD SUCCESS

Related

• Fixes RedisCache with GenericJacksonJsonRedisSerializer breaks when using enums #3306
• Aligns with Jackson's DefaultTyping.NON_FINAL_AND_ENUMS intent
• Enables caching of polymorphic types including enums

[lukman48]

✅ DCO Signature Updated

The commit has been amended with the required DCO (Developer Certificate of Origin) signature.

Changes Made:

• Added Signed-off-by: lukman48 <lukman_uki@yahoo.co.id> line
• Force-pushed updated commit to the branch
• DCO check: ACTION_REQUIRED → SUCCESS ✅

Commit Details:

• Old Hash: bbccb66
• New Hash: 0965640
• Signature: Verified and compliant

PR Status:

• ✅ DCO: SUCCESS
• ✅ Pull-Request check: SUCCESS
• ✅ All tests pass

Ready for maintainer review! 🚀