[Java / Feign] Option to exclude authorization from generated API methods?

Description

In my swagger specification yml, we apply an Authorization parameter (by ref) to each endpoint. It's strictly an opaque OAuth2 bearer token.

When generating a Java Feign API client (same behavior exhibited in pretty much every swagger library I've tested), the authorization key shows up as a parameter to each API method. However, I'd really like to stick to using an Auth interceptor and not having our developers see these authorization parameters everywhere.

Example of the pervasive authorization header in all API methods:

  @RequestLine("DELETE /installedapps/{id}/subscriptions")
  @Headers({
    "Accept: application/json",
    "Authorization: {authorization}"
  })
  SubscriptionDelete deleteAllSubscriptions(@Param("id") String id, @Param("authorization") String authorization);

Swagger-codegen version

"io.swagger:swagger-annotations:1.5.15"
"io.swagger:swagger-codegen-cli:2.4.0"

Swagger declaration file content or url

Swagger codegen config:

{
    "library": "feign",
    "java8": true
}

Swagger spec example

parameters:
  authorization:
    name: Authorization
    in: header
    description: OAuth token
    required: true
    type: string
    format: string
/installedapps/{id}/subscriptions:
    parameters:
    - $ref: '#/parameters/authorization'

Command line used for generation

Gradle plugin that uses swagger-codegen-cli.

Steps to reproduce

• Use aforementioned Swagger yaml
• Generate Java APIs using Feign library
• Observe that all methods require an authorization param

Related issues/PRs

None found

Suggest a fix/enhancement

Perhaps a template change to turn off authorization params being included in the method signatures.

Start with the Feign generation templates and the generated Java method signatures described in the issue, then trace how the Swagger authorization header becomes a method parameter. Define how an option would suppress those parameters while preserving interceptor-based authorization, and verify the behavior by regenerating the example API.