public class Foo {

	@JsonInclude(JsonInclude.Include.NON_NULL)
	protected String hello;

	protected Map<String, Object> additionalFields;

	//Constructors, Getters, & Setters


}

What I'm getting now:
{
	"hello": "23",
	"additionalFields": {
		"field1": "23",
		"field2": "24",
		"key": "value"
	}
}


What I'd like:
{
	"hello": "23",
	"field1": "23",
	"field2": "24",
	"key": "value"
}