[dart][dio][built_value] Fix missing serializer factory builders for additionalProperties

[kuhnroyal]

…additionalProperties

Refactor the addition of custom serializer factories.
Should fix #6951
Should fix #10465

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CC @jaumard (2018/09) @josh-burton (2019/12) @amondnet (2019/12) @sbu-WBT (2020/12) @kuhnroyal (2020/12) @agilob (2020/12) @ahmednfwela (2021/08)

[ahmednfwela]

does dart-dio-next also have this?

[kuhnroyal]

does dart-dio-next also have this?

It is only in dart-dio-next.

[ahmednfwela]

oh I was wondering why I wasn't reproducing this and I forgot I fixed it in my version

https://github.com/Bdaya-Dev/openapi-generator/blob/bdaya_master/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/DartDioNextClientCodegen.java#L527

and apparently #10189 is still not solved ?

[kuhnroyal]

@ahmednfwela We already have the handling for response and parameter types, I just improved it to handle nullability.
This PR mainly adds it for schemas using additionalProperties.

[kuhnroyal]

@jaumard This probably also fixes #10465, can you check that please.

[ahmednfwela]

but why is additionalProperties relevant here ? shouldn't type and items.type be enough ?
is there a case where additionalProperties can contain additional type info ?

Edit: this gets assigned automatically by default codegen https://github.com/Bdaya-Dev/openapi-generator/blob/master/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java#L3813

[kuhnroyal]

See #6951 (comment)
This results in a BuildList<BuildMap<String, JsonObject?>> and there is no builder factory for the map generated atm., only for the list. additionalProperties can lead to nested containers and that is where built_value fails to generate the serializer builders.

This can also be a BuildList<BuildMap<String, int?>> for example.

[ahmednfwela]

yes, but why check for additionalProperties instead of items ?

[kuhnroyal]

Well for normal properties this is automatically generated.

[ahmednfwela]

I see now what you mean, but this is not recursive, so it won't solve BuiltList<BuiltList<BuiltMap<String, JsonObject?>>> for example, right ?

[kuhnroyal]

Correct