Polymorphic subtypes not registering on copied ObjectMapper (2.11.1)

[retrodaredevil]

After upgrading to 2.11.1 from 2.11.0, code that uses a copied ObjectMapper, that then registers subtypes does not work.

Take this simple test case:

import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.annotation.JsonTypeName;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.junit.jupiter.api.Test;

public class JacksonPolymorphicTest {

	@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXISTING_PROPERTY, property = "packetType")
	public interface A {
	}
	@JsonTypeName("myType")
	static class B implements A {
	}
	@Test
	void test() throws JsonProcessingException {
		ObjectMapper objectMapper = new ObjectMapper().copy();
		objectMapper.getSubtypeResolver().registerSubtypes(B.class);
		String json = "{ \"packetType\": \"myType\" }";
		objectMapper.readValue(json, A.class);
	}
}

The above test passes by changing one of two things:

• Remove the .copy() from the ObjectMapper line
• Use Jackson 2.11.0 instead of 2.11.1

Also, I'm aware that the above code does not serialize, but that's not the point right now. I'm just worried about deserialization.

I'm not really sure what the cause is here, but it's something that changed from 2.11.0 to 2.11.1. Maybe it's also affecting other times when the ObjectMapper is copied?

EDIT: This line changed from 2.11.0 to 2.11.1:

jackson-databind/src/main/java/com/fasterxml/jackson/databind/ObjectMapper.java

Line 560 in 56b4421

_subtypeResolver = src._subtypeResolver.copy();

This may have been affected by changes from: #2755

[cowtowncoder]

Thank you for reporting this, and especially for investigation and fix! It is unfortunate that the fix to copy problem lead to this regression.

I'll have a look at PR to verify it (sounds legit). One other thing I will need to be able to merge PR is CLA:

https://github.com/FasterXML/jackson/blob/master/contributor-agreement.pdf

(unless I have asked and received one earlier; one is good for all contributions)

which is easiest to print, fill & sign, scan/photo, email to info at fasterxml dot com.
Once I get it, I can merge the PR and get in for 2.11.2.

[retrodaredevil]

Ok, I emailed the CLA to info@fasterxml.com.

[cowtowncoder]

Thank you! I merged PR changes manually, and the fix will be included in 2.11.2 (which unfortunately will take a while as 2.11.1 was just released -- but 2.12.2-SNAPSHOT is available via Sonatype's OSS repo)