[BUG] Separate Model option doesn't seem to be working as expected

[EmmanuelAdeiza]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce

1. Use the following build.yaml configuration:

  $default:
    builders:
      swagger_dart_code_generator:
        options:
          input_folder: "swagger_input_folder/"
          output_folder: "lib/models/generated"
          separate_models: true

2. Place a Swagger/OpenAPI file in the specified input_folder.
3. Run the build command:
   dart run build_runner build --delete-conflicting-outputs
4. Observe the generated files in the output_folder.

Expected behavior
Each model should be generated in a separate file within the output_folder when separate_models: true is set in the configuration.

Swagger specification link
Link to swagger/OpenApi documentation

Library version used:
3.0.1

Additional context
Add any other context about the problem here.

[EmmanuelAdeiza]

Correct me if I am wrong but separate_models should generate each model in a separate file.