Empty String for Date

[oleg-andreyev]

Jane version(s) affected: 7.5.4

Description

Based on openapi documentation https://swagger.io/docs/specification/data-models/data-types/#string

Note that an empty string "" is a valid string unless minLength or pattern is specified.

but generated Normalizer does not respect it.
Normalizer just validate that key exists, but does not validate empty, pattern or minLength

How to reproduce

                    "estimated_collection_date" : {
                      "type" : "string",
                      "format" : "date",
                      "pattern" : "yyyy-mm-dd",
                      "description" : "Date of collection for shipment"
                    },
                    "estimated_delivery_date" : {
                      "type" : "string",
                      "format" : "date",
                      "pattern" : "yyyy-mm-dd",
                      "description" : "Date of delivery for shipment, if present"
                    },

and JSON response with estimated_collection_date or estimated_delivery_date as empty string