How can you generate 'properties' entry, even for Classes without fields?

[sashirestela]

Is there any configuration parameter to generate the properties entry, even for Classes without fields?

For example, for the following class:

class EmptyClass {
}

Currently, I'm getting this:

{
    "type":"object"
}

But I want to get this one:

{
    "type":"object",
    "properties":{}
}

This is my Java code:

var jacksonModule = new JacksonModule(JacksonOption.RESPECT_JSONPROPERTY_REQUIRED);
var configBuilder = new SchemaGeneratorConfigBuilder(SchemaVersion.DRAFT_2020_12,
        OptionPreset.PLAIN_JSON)
        .with(jacksonModule)
        .without(Option.SCHEMA_VERSION_INDICATOR);
var config = configBuilder.build();
var generator = new SchemaGenerator(config);
var jsonSchema = generator.generateSchema(myClass);

[CarstenWickner]

Hi @sashirestela,

While there is no standard Option for it or anything, you can achieve that of course:

// add the properties keyword to all empty object definitions
configBuilder.forTypesInGeneral().withTypeAttributeOverride((node, scope, context) -> {
    JsonNode typeValue = node.get(context.getKeyword(SchemaKeyword.TAG_TYPE));
    String objectTypeValue = context.getKeyword(SchemaKeyword.TAG_TYPE_OBJECT);
    if (typeValue == null || node.has(context.getKeyword(SchemaKeyword.TAG_PROPERTIES))) {
        // nothing to do here
    } else if (typeValue.isTextual() && objectTypeValue.equals(typeValue.textValue())) {
        node.putObject(context.getKeyword(SchemaKeyword.TAG_PROPERTIES));
    } else if (typeValue.isArray()) {
        for (JsonNode singleTypeValue : typeValue) {
            if (objectTypeValue.equals(singleTypeValue.textValue())) {
                node.putObject(context.getKeyword(SchemaKeyword.TAG_PROPERTIES));
                return;
            }
        }
    }
});

That being said: why would you want this?
It's not changing the schema in any meaningful way. An empty "properties" node is redundant/inconsequential, isn't it?

[sashirestela]

Thanks for your answer @CarstenWickner. From a Json-schema point of view you are right, however, in my context I need empty properties. I'm working in a Java integration with OpenaAI called simple-openai and I'm using classes to describe functions which are going to be used in chats and OpenAI is expecting an empty value when functions does not have parameters (or the same when the class describing the function does not have fields):

https://community.openai.com/t/parameters-property-isnt-optional-as-theyve-mentioned-in-doc/265256