OpenApiMixin extensions should include Null values

[loomisdf]

Summary

Ran into this issue while working with springdocs-openapi springdoc/springdoc-openapi#1525
Null vendor exensions are allowed via the OpenAPI spec detailed here

The extension value can be a primitive, an array, an object or null

However, they are not being rendered because the OpenApiMixins class is not setup to do so.

Expected Output

"x-my-vendor-extensions": {
	"property1": "value1",
        "property2": null
}

Actual Output

"x-my-vendor-extensions": {
	"property1": "value1"
}

Solution

I believe the @JsonInclude(value = Include.ALWAYS) annotation should be added here.

@JsonAnyGetter
@JsonInclude(value = Include.ALWAYS)
public abstract Map<String, Object> getExtensions();

A similar workaround has been added to the springdocs-openapi project.

[ponelat]

@HugoMario could you take a look into fixing this, if it's still an issue. Thanks!

[HugoMario]

fixed by #4468