[BUG] relative path is prefixed with spec-url

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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Description

When you generate with specs from URL the url is prefixed to the relative path from spec. From #10697 i would assume that a relative server-url is used as basePath in generated code.

openapi-generator version

5.4.0
5.3.1

OpenAPI declaration file content or url

https://petstore3.swagger.io/api/v3/openapi.json

Generation Details

The generator is used from npms @openapitools/openapi-generator-cli version 2.4.26
Via openapi-generator-cli version-manager list I choosed the versions mentioned above - same result.

Steps to reproduce

openapi-generator-cli generate -g typescript-angular -o /tmp/api -i https://petstore3.swagger.io/api/v3/openapi.json

The file /tmp/api/api/pet.service.ts looks as following:

...
export class PetService {

    protected basePath = 'https://petstore3.swagger.io/api/v3';
...

expected is

...
export class PetService {

    protected basePath = '/api/v3';
...

as "servers":[{"url":"/api/v3"} suggests

Related issues/PRs

#10057

Suggest a fix

Take the servers-url as-is for generating the basePath

Start by running the documented openapi-generator-cli command with https://petstore3.swagger.io/api/v3/openapi.json and inspect /tmp/api/api/pet.service.ts. Trace how the relative servers URL becomes the generated basePath for typescript-angular. Done means the generated service uses /api/v3 rather than the full spec URL.