Unexpected @JsonIgnore Annotation Application on Custom isXxx() Method with Non-Boolean Field

[fengziboboy]

Description of the Issue

Upon utilizing the Jackson library for serialization of a Java Bean, it has been observed that a custom isXxx() method annotated with @JsonIgnore is inappropriately applied to a non-Boolean field, resulting in the field's omission from the serialized output.

Steps to Reproduce

1. Create a Java Bean Class:

// Bean Class
@Data
public class MyBean {
    private Integer enhanceChances;

    @JsonIgnore
    public boolean isEnhanceChances() {
        // Method Implementation
    }
}

2. Serialize the Bean:

// Serialization Code
ObjectMapper mapper = new ObjectMapper();
MyBean bean = new MyBean();
String json = mapper.writeValueAsString(bean);

Expected Behavior

• Serialization Inclusion: It is expected that the Jackson serializer would disregard the custom isEnhanceChances() method and instead utilize the Lombok-generated getEnhanceChances() method, thereby including the enhanceChances field in the serialized output.

Actual Behavior

• Serialization Exclusion: Contrary to expectations, the Jackson serializer prioritizes the isXxx() method naming convention, applies the @JsonIgnore annotation, and consequently excludes the enhanceChances field from the serialized output.

Environment Information

• Jackson Version: 2.x.x
• Lombok Version: 1.x.x
• Java Version: 11+
• Relevant Dependencies:

<dependencies>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.15.2</version>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.16</version>
    </dependency>
</dependencies>

Relevant Code Snippet

Refer to the PropertyBuilder class within the Jackson library, specifically the loop iterating over getter methods:

for (AnnotatedMethod m : _classDef.memberMethods()) {
 ...

implName = ai.findImplicitPropertyName(m);
            if (implName == null) {
                implName = _accessorNaming.findNameForRegularGetter(m, m.getName());
            }
            if (implName == null) { // if not, must skip
                implName = _accessorNaming.findNameForIsGetter(m, m.getName());
                if (implName == null) {
                    return;
                }
                visible = _visibilityChecker.isIsGetterVisible(m);
            } else {
                visible = _visibilityChecker.isGetterVisible(m);
            }
        }

Note: This code snippet highlights the potential source of the issue, where the isXxx() naming convention is prioritized over the getXxx() convention for non-Boolean fields.

[JooHyukKim]

Hmmm, this could be caused by Lombok-generated class files in a shape u do not expect.

Could u try without Lombok and see how it does?

[fengziboboy]

I tried removing Lombok and add getEnhanceChances(), but the issue still exists.
（Lombok generates the getXXX methods for Integer fields, and I overlooked the isXXX methods. ）
When I changed isEnhanceChances() to enableEnhanceChances(), the issue was resolved.
Therefore, the problem lies with Jackson

[cowtowncoder]

Right, behavior is imposed by Jackson and is as intended.

[cowtowncoder]

This is behaving as intended: only name of field needs to match accessor-implied name; types not.
(there is logic for requiring boolean or Boolean for "is-getter"s, however -- but getter/setter/field types need not match; also note there is MapperFeature.ALLOW_IS_GETTERS_FOR_NON_BOOLEAN to allow non-boolean-valued getters)

So this is behaving as designed. If you want to include field in such case, add separate @JsonProperty (in addition to @JsonIgnore on accessor).

[fengziboboy]

Alright, I just want to ignore this custom isXXX method. since serialization doesn't require matching types, an Integer field named XXX has been ignored.

Since this is behaving as intended.
I had to avoid the custom method name being the same as the field name (starting with get/set/is).
Thanks.

[cowtowncoder]

Correct. Thank you for the update.