Hello, I am using Mapstruct to transform data from a JSON format to an XML format for a project at my company. I'm running into some edge case issues where Mapstruct will return an object whose fields are all null, and as such whenever I marshal the object to XML it will come as an empty tag.

e.g. as below:

<Parent>
    <Child/> <!-- A child object whose fields are all null -->
    <Child>
        <FirstName>FirstName</FirstName>
        <LastName>LastName</LastName>
    </Child>
</Parent>

I would like a way that I could add a custom isAllFieldsNull check at the end of each generated mapping function which would return the object if false or null if true.

@Override
public ChildXML childJSONToChildXML(ChildJSON childJSON) {
    if ( childJSON == null ) {
        return null;
    }

    ChildXML childXML = new ChildXML();

    // ... map properties

    // here is where I would like to be able to add a custom check
    if ( isAllFieldsNull(childXML) ) {
        return null;
    }
   
    return childXML;
}

I realize this can be resolved with a simple XSLT that removes empty tags, but I also have other requirements such as elements that need to be returned as empty. Please let me know if this check is able to be added in the current implementation of Mapstruct or if this is a feature request that can be added.

Thanks.