Mapper in 3.0.0 does not match property with second letter capitalized to getter/setter for incompatible getter/setter (see #2882)

[alexgrech4]

Search before asking

• I searched in the issues and found nothing similar.

Describe the bug

If a property with a capitalized second letter (i.e. String aProp;) has a getter/setter whose name has not changed the prop name (i.e. getaProp() and setaProp()) the property will not be properly serialized/deserialized. This is true whether or not the mapper feature MapperFeature.FIX_FIELD_NAME_UPPER_CASE_PREFIX is enabled or disabled.

Version Information

3.0.0

Reproduction

public class TestPojo {
    private String aProp;
    private String anotherProp;

    public String getaProp() {
        return aProp;
    }

    public void setaProp(String aProp) {
        this.aProp = aProp;
    }

    public String getAnotherProp() {
        return anotherProp;
    }

    public void setAnotherProp(String anotherProp) {
        this.anotherProp = anotherProp;
    }
}

public void featureEnabledTest() {

  ObjectMapper mapper = JsonMapper.builder().enable(MapperFeature.FIX_FIELD_NAME_UPPER_CASE_PREFIX).build();

  String json = "{\"aProp\":\"aPropValue\", \"prop1\":\"prop1Value\"}";
  TestPojo result = mapper.readValue(json, TestPojo.class);
  assert "aPropValue".equals(result.getaProp()); //fails

  String serialized = mapper.writeValueAsString(result);
  assert serialized.equals(json);
}

public void featureDisabledTest() {

  ObjectMapper mapper = JsonMapper.builder().disable(MapperFeature.FIX_FIELD_NAME_UPPER_CASE_PREFIX).build();

  String json = "{\"aProp\":\"aPropValue\", \"prop1\":\"prop1Value\"}";
  TestPojo result = mapper.readValue(json, TestPojo.class);
  assert "aPropValue".equals(result.getaProp()); //fails

  String serialized = mapper.writeValueAsString(result);
  assert serialized.equals(json);
}

Expected behavior

No response

Additional context

This was not an issue in 2.20.0, but has become one since migrating to 3.0.0.

[cowtowncoder]

One thing to try to debug this is to enable DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES to see where the mismatch is. I suspect the issue is partly in 3.0 default of FAIL_ON_UNKNOWN_PROPERTIES being false which can hide mismatches.

[alexgrech4]

With DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES enabled I get the following exception:

tools.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized property "aProp" (class test.tests.PropNameTest$TestPojo), not marked as ignorable (one known property: "anotherProp")
 at [Source: REDACTED (`StreamReadFeature.INCLUDE_SOURCE_IN_LOCATION` disabled); byte offset: #UNKNOWN] (through reference chain: test.tests.PropNameTest$TestPojo["aProp"])

It appears aProp is not being recognized as a property.

[JooHyukKim]

Strange, Lemme try looking into it.

[JooHyukKim]

@alexgrech4 Can you check again?

I wrote #5358 against 2.x version ? Test fails either way

With DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES....

• disabled , would fail like the PR
• enabled fail how you say tests do

PS: 2.x or 2.20 version still same failures

[alexgrech4]

@JooHyukKim Sorry, there were some issues with my reproduction code.
The json String to test should be String json = "{\"aProp\":\"aPropValue\",\"anotherProp\":\"anotherPropValue\"}"
With that change, I'm seeing the tests pass on 2.20

[cowtowncoder]

@alexgrech4 and on 3.0.0?

Btw, this is EXACTLY why I always prefer DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES enabled for tests. Disabling it (which, alas, users prefer) in 3.0 is causing many invalid bug reports (or at least missing info).

[alexgrech4]

@cowtowncoder still failing for me on 3.0.0

Btw, this is EXACTLY why I always prefer DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES enabled for tests. Disabling it (which, alas, users prefer) in 3.0 is causing many invalid bug reports (or at least missing info).

Having DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES enabled is how I was able to spot this issue when migrating from 2.20.0 to 3.0.0. I usually prefer it on as well, for the reproduction code I just wanted it to be the simplest test case I could make.

[cowtowncoder]

@alexgrech4 Ok. That makes sense, my bad.

Just to make sure: is the initial reproduction exactly as-is to repro the problem?

EDIT: I think it is, seem to be able to repro fo 3.0.

[cowtowncoder]

Ahh, I'm afraid this is a Feature-not-Bug -> #2882: methods getaProp() and setaProp() are no longer recognized as property accessors and must be explicitly annotated.

    @JsonPropertyOrder({ "aProp" })
    static class TestPojo {
        private String aProp;
        private String anotherProp;

        // Needed in 3.0 due to incompatible naming
        @JsonProperty("aProp")
        public String getaProp() {
            return aProp;
        }

        // Needed in 3.0 due to incompatible naming
        @JsonProperty("aProp")
        public void setaProp(String aProp) {
            this.aProp = aProp;
        }

        public String getAnotherProp() {
            return anotherProp;
        }

        public void setAnotherProp(String anotherProp) {
            this.anotherProp = anotherProp;
        }
    }

[cowtowncoder]

Added an entry on

https://github.com/FasterXML/jackson/wiki/Jackson-Release-3.0#behavioral-changes

to mention this.

In hindsight, it'd have made sense add MapperFeature to enable/disable this.

But there is a way to allow such names; let's see (from #2882 PR b7e2be5)

JsonMapper mapper = JsonMapper.builder()
    .accessorNaming(new DefaultAccessorNamingStrategy.Provider()
        // withFirstCharAcceptance(boolean allowLowerCaseFirstChar, boolean allowNonLetterFirstChar)
        .withFirstCharAcceptance(true, false))
    .build();

I modified IPhoneStyleProperty5335Test.java to use these settings to allow non-standard naming for getters/setters (wrt capitalization of the 1st char)