Reading into existing instance uses creator property setup instead of accessor

[odrotbohm]

Search before asking

• I searched in the issues and found nothing similar.

Describe the bug

When reading into an existing object, the JsonMapper uses the deserializer of the creator property instead of the parameter of the accessor.

package example.three;

import static org.assertj.core.api.Assertions.*;

import tools.jackson.databind.json.JsonMapper;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.stream.Stream;

import org.junit.jupiter.api.DynamicTest;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestFactory;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonUnwrapped;

class Jackson3Test {

  @Test
  void readsIntoCreator() throws Exception {

    var mapper = JsonMapper.builder()
        .build();

    mapper.readerForUpdating(new ArrayListHolder("A")).readValue("""
        {
          "values" : [ "A", "B" ]
        }
        """);
  }

  public static class ArrayListHolder {
    Collection<String> values;

    ArrayListHolder(String... values) {
      this.values = new ArrayList<>(Arrays.asList(values));
    }

    public void setValues(Collection<String> values) {
      this.values = values;
    }
  }
}

Stack trace:

tools.jackson.databind.DatabindException: Cannot cast [Ljava.lang.String; to java.util.Collection
 at [Source: REDACTED (`StreamReadFeature.INCLUDE_SOURCE_IN_LOCATION` disabled); byte offset: #UNKNOWN] (through reference chain: example.three.Jackson3Test$ArrayListHolder["values"])
	at tools.jackson.databind.DatabindException.wrapWithPath(DatabindException.java:111)
	at tools.jackson.databind.deser.bean.BeanDeserializerBase.wrapAndThrow(BeanDeserializerBase.java:1850)
	at tools.jackson.databind.deser.bean.BeanDeserializer.deserialize(BeanDeserializer.java:288)
	at tools.jackson.databind.deser.DeserializationContextExt.readRootValue(DeserializationContextExt.java:267)
	at tools.jackson.databind.ObjectReader._bindAndClose(ObjectReader.java:1702)
	at tools.jackson.databind.ObjectReader.readValue(ObjectReader.java:1220)
	at example.three.Jackson3Test.readsIntoCreator(Jackson3Test.java:102)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
Caused by: java.lang.ClassCastException: Cannot cast [Ljava.lang.String; to java.util.Collection
	at java.base/java.lang.Class.cast(Class.java:4067)
	at tools.jackson.databind.deser.impl.MethodProperty.set(MethodProperty.java:179)
	at tools.jackson.databind.deser.CreatorProperty.deserializeAndSet(CreatorProperty.java:219)
	at tools.jackson.databind.deser.bean.BeanDeserializer.deserialize(BeanDeserializer.java:286)
	... 7 more

Works on Jackson 2.

Version Information

3.0 RC8

Reproduction

No response

Expected behavior

No response

Additional context

No response

[cowtowncoder]

Thank you for reporting this.

I would expect this to fail for 2.x too, but will mark as 3.x as per report.

[JooHyukKim]

Wrote #5286 to verify indeed it did not work since 2.18.
Few questions tho, @cowtowncoder

1. this should work without annotating Collection<String> values; with @JsonMerge?
2. Also, when working, should it be MergingSettableBeanProperty that takes care of handling?

Then I can go take a look deeper