@JsonProperty and equivalents should merge with AnnotationIntrospectorPair

[cowtowncoder]

Describe your Issue

If a property has multiple naming annotations -- such as standard @JsonProperty, and @JacksonXmlProperty from jackson-dataformat-xml -- and there are 2 AnnotationIntrospectors, then AnnotationIntrospectorPair should merge parts so that if the Primary introspector has no value (empty String or null), value from secondary should be used, for:

1. Local name
2. Namespace

so that, for example:

@JacksonXmlProperty(isAttribute=true)
@JsonProperty(namespace="uri:ns1", value="prop")
public int value;

where first annotation has precedence (annotation introspector that handles it is the first introspector configured for AnnotationIntrospectorPair) we should have localName and namespace from @JsonProperty since JacksonXmlProperty defines neither (that is, has defaults of "").
Currently this is not the case.

[SimonCockx]

This changed existing behaviour, which is currently causing us trouble. Any advice on how to migrate?

We have a custom XML annotation introspector which explicitly sets the wrapper name to Property.NO_NAME if our custom annotation is present and the type is a list:

    @Override
    public PropertyName findWrapperName(Annotated ann) {
        if (ann.hasAnnotation(RosettaAttribute.class) && hasCollectionType(ann)) {
            // Disable wrapping of lists.
            return PropertyName.NO_NAME;
        }
        return super.findWrapperName(ann);
    }

This used to work in Jackson 2.15.

Unfortunately, due to this change, PropertyName.NO_NAME is now merged with PropertyName.DEFAULT from the default Jackson XML annotation introspector, and the new behaviour prefers PropertyName.DEFAULT over PropertyName.NO_NAME. The previous behaviour would prefer PropertyName.NO_NAME.

I have not found a way to fix this. Is there a way to get rid of the default annotation processor? Should I raise an issue?

[cowtowncoder]

@SimonCockx you should file an issue for jackson-dataformat-xml, referencing this issue. And including version you are using (2.17.1 perhaps).

One way you could avoid this would be to sub-class AnnotationIntrospectorPair, combine introspector explicitly (I assume you need 2 AnnotationIntrospectors?). Or use/create single AnnotationIntrospector.
But logic of combining may hard to override.

[SimonCockx]

@cowtowncoder Thanks for the response. Actually I only need one, but I have not found a way to disable the default annotation processor, which seems to be somewhat "hardcoded" in the basicConfig when constructing an ObjectMapper. But let's maybe continue this thread in the new issue.

[cowtowncoder]

NOTE: #4595 changes behavior for 2.17.2 to not merge NO_NAME case.