If field "SupplierNumber" is mandatory in "Procurement - Create one supplier" REST API request

Summary:

In the link https://docs.oracle.com/en/cloud/saas/procurement/22d/fapra/op-suppliers-post.html, it shows a filed "SupplierNumber(required): string" in "Request Body - application/json (schema)".

But in "Example Request Body", the filed "SupplierNumber" is not specified. I also verified the same in my test env that when "SupplierNumber" was not offered in "create one supplier", "201 Created" was returned and supplier was created successfully.

Content (required):

So what does the "required" mean in the API specification?

Thanks.