[HASKELL] Definitions which are arrays generate empty types

Description

When generating a haskell-http-backend API client from an API file that contains one or more definitions which are type: array, the resulting Haskell types will be empty.

The Haskell types should contain a list of the array item type, or otherwise be a newtype or type alias for the type [<array item item>]. Instead, the definition which is an array will have an empty datatype generated for it.

Because of this bad generation, some API clients generated by swagger-codegen are unusable.

Swagger-codegen version

2.4.21. (Latest stable 2.0 at time of writing).

Swagger declaration file content or url

A minimal example can be found here

Command line used for generation

swagger-codegen generate -i bad_swagger_example.yaml --additional-properties cabalPackage=test-haskell -l haskell-http-client -o test-haskell/

Steps to reproduce

1. Run the above command, or any similar one, to generate a haskell-http-client backend for the provided example YAML.
2. Open test-haskell/lib/Test/Model.hs.
3. See that the definition of the data type Foo does not contain a list of Bar (i.e. a [Bar]), as expected.

Related issues/PRs

Looks related to #10559

Suggest a fix/enhancement

Run the documented swagger-codegen command with the linked minimal Swagger example, then inspect test-haskell/lib/Test/Model.hs and compare the generated Foo and Bar definitions. Done means an array definition generates a Haskell type containing the item list type, such as [Bar], rather than an empty datatype.