[BUG] [typescript-axios] The `nullSafeAdditionalProps` option should also work on objects with specified keys.

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

In the object schema, nullSafeAdditionalProps is applied correctly when additionalProperties is set as a single property. However, if there are predefined keys and additionalProperties is defined, it generates them as required in their type.

this makes type error

• test

• test-2

openapi-generator version

7.0.1

OpenAPI declaration file content or url

openapi: "3.0.0"
info:
  title: "title"
  version: "1.0.0"
paths:
  /test:
    get:
      responses:
        "200":
          description: "200 OK"
          content:
            application/json:
              schema:
                type: "object"
                properties:
                  data:
                    type: "object"
                    properties:
                      a:
                        type: "boolean"
                      b:
                        type: "boolean"
                    additionalProperties:
                       type: "boolean"
  /test-2:
    get:
      responses:
        "200":
          description: "200 OK"
          content:
            application/json:
              schema:
                    additionalProperties:
                       type: "boolean"

Generation Details

{
    "$schema": "./node_modules/@openapitools/openapi-generator-cli/config.schema.json",
    "spaces": 2,
    "generator-cli": {
        "version": "7.0.1",
        "generators": {
            "typescript-axios": {
                "glob": "api-specs/*.yaml",
                "output": "#{cwd}/src/service/#{name}",
                "generatorName": "typescript-axios",
                "additionalProperties": {
                    "useSingleRequestParameter": true,
                    "nullSafeAdditionalProps": true
                }
            }
        }
    }
}

Steps to reproduce

use embeded yaml to codegen

Related issues/PRs

Suggest a fix

Shouldn't the properties be declared as optional with '?' in the key declaration, even without nullSafeAdditionalProps?

https://github.com/OpenAPITools/openapi-generator/blob/2f655f1a9cec1f69bcd3487ea67d0d137dd7ac8d/modules/openapi-generator/src/main/resources/typescript-axios/modelGeneric.mustache#L8

Start with the embedded OpenAPI YAML and generator-cli configuration, then inspect modules/openapi-generator/src/main/resources/typescript-axios/modelGeneric.mustache at the linked line. Generate the TypeScript Axios models for both object schemas and compare the property declarations. Done means nullSafeAdditionalProps also produces usable types for objects with predefined keys without the reported type error.