How to use custom data types as body parameters for POST API request

I want to do a POST API request and want to add a body. I saw that you can create variables. Unfortunately variables can only have basic datatypes (i.e. String, Boolean, Integer, ...) and not Datatype (the one that you can create). This would lead me to provide every property of my custom datatypes as dedicated variable. How can I avoid this? Here is an example:

Datatype Property

{
    uuid: string,
    title: string,
    street: string,
    housenumber: integer,
    postalCode: string,
    city: string
}

I would like to have a single variable in my API Body (i.e. propery) of Datatype propery and not have six variables.

Is there also a way to transform the property to json via a custom function and use this instead?