[BUG][JAVA] Client generator ignores 'nullable' property

Description

Client generator ignores ‘nullable’ property of the object schema. Instead, javax.annotation.Nullable generation seems to be based on ‘required’ property. This behaviour is incorrect - required fields have to be provided, but not necessarily non-null, i.e { "field" : null } satisfies the ‘required’.

Nullable is part of OpenAPI 3.0 spec. To make it more robust, x-nullable could be handled, too.

OpenAPI declaration file content or url

"components": {
   "schemas": {
      "SomeEntity": {
        "type": "object",
        "properties": {
          "name": {
            "id": "string",
            "nullable": false
          }
      }
   }
}

Related issues/PRs

https://github.com/OpenAPITools/openapi-generator/issues/3264

[alwaysbemark]

The semantics posted by @kkosmrli are what I would expect too. This issue is also impacting us and requires manual post-processing of the generated files. It would be nice to get a fix for this. Thank you!

[kkosmrli]

I also ran into this behaviour today. At the moment it seems the only option is to use required to mark fields with @NotNull. Unfortunately this means that the generated code does not match the specification. According to OAS 3 required just marks a field as mandatory in the object e.g. {"field" : null} and {"field" : "value"} is valid and {} is not.