Question: base_path included in Path object

Have a question around the 'Path' object for individual endpoints.

The grape setup is similar to the one in api_swagger_v2_global_configuration_spec

module TheApi
  class ConfigurationApi < Grape::API
    format :json
    prefix: 'somewhere/over/the/rainbow'
    version 'v3', using: :path

    desc 'This returns something',
    get :something do
      { 'something' => :foo }
    end

    add_swagger_documentation format: :json,
                              base_path: -> { 'somewhere/over/the/rainbow' },
                              add_base_path: true,
end

Reading the Swagger specification for path objects and the description for the Path Item Object

A relative path to an individual endpoint

I would expect the doc to have the output of this:

{"info"=>{"title"=>"API title"},
 "swagger"=>"2.0",
 "produces"=>["application/json"],
 "host"=>"another.host.com",
 "basePath"=>"somewhere/over/the/rainbow",
 "schemes"=>["http"],
 "tags"=>
  [{"name"=>"configuration",
    "description"=>"Operations about configurations"}],
 "paths"=>
  {"/v3/configuration"=>
    {"get"=>
      {"summary"=>"This returns something",
       "description"=>"This returns something",
       "produces"=>["application/json"],
       "tags"=>["configuration"],
       "operationId"=>"getSomewhereOverTheRainbowV3Configuration"
}}}}

vs. the current one of

{"info"=>{"title"=>"API title"},
 "swagger"=>"2.0",
 "produces"=>["application/json"],
 "host"=>"another.host.com",
 "basePath"=>"somewhere/over/the/rainbow",
 "schemes"=>["http"],
 "tags"=>
  [{"name"=>"configuration",
    "description"=>"Operations about configurations"}],
 "paths"=>
  {"/somewhere/over/the/rainbow/v3/configuration"=>
    {"get"=>
      {"summary"=>"This returns something",
       "description"=>"This returns something",
       "produces"=>["application/json"],
       "tags"=>["configuration"],
       "operationId"=>"getSomewhereOverTheRainbowV3Configuration"
}}}}

Or is there any other way to achieve this without changes to the current code?
Or am I misinterpreting the spec?

Start with spec/swagger_v2/api_swagger_v2_global_configuration_spec.rb, which the issue uses as its setup, and compare the generated paths with the Swagger Path Item Object expectation described here. Trace how base_path and the endpoint prefix are represented, then add or update a focused specification so the intended path output is explicit and passing.