[BUG] (Dart-Dio) import-mappings are ignored in some import statements

[bw-flagship]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator?
• 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

--import-mappings in dart-dio only works partially. Model files that reference the mapped type get the correct custom import, but serializers.dart and the barrel file (<pub>.dart) always hardcode the model/ path. The mapped model file itself is also still generated even though it shouldn't be.

I tried --schema-mappings and --model-name-mappings as well, same result.

We're currently working around this with sed + rm after generation, which works but is ugly.

openapi-generator version

7.17.0 (Homebrew), also reproduced on latest master.

OpenAPI declaration file content or url

openapi: "3.1.0"
info:
  title: Example
  version: "1.0.0"
paths:
  /orders:
    get:
      operationId: getOrders
      responses:
        "200":
          description: OK
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/OrderOut"
components:
  schemas:
    Address:
      type: object
      required: [street, city]
      properties:
        street:
          type: string
        city:
          type: string
    OrderOut:
      type: object
      required: [id, shippingAddress]
      properties:
        id:
          type: integer
        shippingAddress:
          $ref: "#/components/schemas/Address"

Generation Details

openapi-generator generate \
  -i spec.yaml \
  -g dart-dio \
  -o out/ \
  --type-mappings "Address=CustomAddress" \
  --import-mappings "CustomAddress=package:my_api/src/custom_models/custom_address.dart"

Steps to reproduce

1. Save the spec above as spec.yaml.
2. Run the generation command.
3. Check the imports in the generated files:

out/lib/src/model/order_out.dart — works, picks up the custom path:

import 'package:my_api/src/custom_models/custom_address.dart';

out/lib/src/serializers.dart — ignores the mapping, uses the default model/ path:

import 'package:my_api/src/model/custom_address.dart';

out/lib/my_api.dart (barrel) — same problem:

export 'package:my_api/src/model/custom_address.dart';

out/lib/src/model/custom_address.dart is also generated even though it should be skipped for import-mapped types.

Related issues/PRs

Suggest a fix

I traced this to two mustache templates that loop over all models and always emit model/<classFilename>.dart, without checking import mappings:

serializers.mustache:

{{#models}}{{#model}}import 'package:{{pubName}}/{{sourceFolder}}/{{modelPackage}}/{{classFilename}}.dart';
{{/model}}{{/models}}

lib.mustache:

{{#models}}{{#model}}export 'package:{{pubName}}/{{sourceFolder}}/{{modelPackage}}/{{classFilename}}.dart';
{{/model}}{{/models}}

These need to skip (or redirect) import-mapped models. The generator should also suppress the model file for these types, similar to how it already skips free-form objects.