[BUG] PHP Symfony server generator forces return type of actions to be an array

Created by: ivan-aksamentov

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

php-symfony server generator produces incorrect return type annotations for actions: for object types, it will erroneously generate an annotation for the type that is an array of these objects, which produces runtime errors on some configurations of Symfony.

For example, for a request that returns Foo, instead of generating type annotation as Foo it will generate type annotation Foo[].

To demonstrate, given the default Pet Store swagger 2.0 contract, where getPetById operation returns a single object of type Pet (only relevant parts are preserved):

swagger: "2.0"

paths:
  /pet/{petId}:
    get:
      tags:
        - "pet"
      summary: "Find pet by ID"
      description: "Returns a single pet"
      operationId: "getPetById"
      responses:
        200:
          description: "successful operation"
          schema:
            $ref: "#/definitions/Pet"

definitions:
  Pet:
    type: "object"

...the generated Symfony action getPetById will be erroneously annotated to return an array. Notice @return OpenAPI\Server\Model\Pet[]:

/**
 * Operation getPetById
 *
 * Find pet by ID
 *
 * @param  int $petId  ID of pet to return (required)
 * @param  integer $responseCode     The HTTP response code to return
 * @param  array   $responseHeaders  Additional HTTP headers to return with the response ()
 *
 * @return OpenAPI\Server\Model\Pet[]
 *
 */
public function getPetById($petId, &$responseCode, array &$responseHeaders);

openapi-generator version

I am using npm package for 4.0.3: "@openapitools/openapi-generator-cli": "0.0.16-4.0.3" But the issue is present on master and v5 branches too.

OpenAPI declaration file content or url

I used the Swagger 2.0 Pet Store example: https://github.com/ivan-aksamentov/openapi-generator-symfony-array-bug-repro/blob/57c538bc7d/petstore.yml

Command line used for generation

openapi-generator generate -g php-symfony -i petstore.yml -o generated/

Steps to reproduce

One can reproduce this issue with this example repository: https://github.com/ivan-aksamentov/openapi-generator-symfony-array-bug-repro

using the following steps (git, java, node and yarn are required):

git clone https://github.com/ivan-aksamentov/openapi-generator-symfony-array-bug-repro
cd openapi-generator-symfony-array-bug-repro
yarn install
yarn generate

After generation, inspect generated/Api/PetApiInterface.php#L121-L133: https://github.com/ivan-aksamentov/openapi-generator-symfony-array-bug-repro/blob/57c538bc7d/generated/Api/PetApiInterface.php#L121-L133

Related issues/PRs

Could not find ones

Suggest a fix

The bug is in this snippet in PhpSymfonyServerCodegen.java#L405-L415:

https://github.com/OpenAPITools/openapi-generator/blob/dd0c2a84ee348e4142936b5666ad843e0a5f4c4a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpSymfonyServerCodegen.java#L405-L415

Note how any non-primitive return type turns into an array:

if (!op.returnTypeIsPrimitive) {
    op.vendorExtensions.put("x-commentType", op.returnType + "[]");
}

I submitted PR #3515 that attempts to fix this issue.