We can download OpenAPI schema from https://developers.fivetran.com/openapi/reference/v1/overview/

`properties` of JSON schema is OPTIONAL by default and if it is REQUIRED, it is necessary to add `required` which is list of required property names.

source: https://json-schema.org/understanding-json-schema/reference/object.html#required-properties

By default, the properties defined by the properties keyword are not required. However, one can provide a list of required properties using the required keyword.

For example, GET response of /v1/users is defined as following.

"responses": {
          "200": {
            "description": "Successful response",
            "content": {
              "application/json": {
                "schema": {
                  "properties": {
                    "code": {
                      "type": "string",
                      "description": "Response status code"
                    },
                    "message": {
                      "type": "string",
                      "description": "Response status text"
                    },
                    "data": {
                      "properties": {
                        "items": {
                          "type": "array",
                          "description": "The collection of return items",
                          "items": {
                            "$ref": "#/components/schemas/UserResponse"
                          }
                        },
                        "nextCursor": {
                          "type": "string",
                          "description": "The value of the cursor parameter for the next page"
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }

When I use this as client (like with codegen) I need to check existence of every properties to strictly follow typings.

More specific example, in typescript, it is expressed as following.

type Response = {
  code?: string;
  message?: string;
  data?: {
    items?: UserResponse[];
    nextCursor?: string;
  };
};

NOTE: Imagine UserResponse is defined in another place.

nextCursor could be actually OPTIONAL.

And if I use the value of this type, I should check everything.

if (response.data != null) {
  if (response.data.items != null) {
    for (const item of response.data.items) {
      if (item.<some item's prop> != null) ...;
      if (item.<other item's prop> != null) ...;
      if (item.<other item's prop> != null) ...;
    }
  }
}

To solve this, I want it to add `required` correctly.

https://json-schema.org/understanding-json-schema/reference/object.html#required-properties

---

Or are they all actually optional?