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

the same issue with #2731

openapi-generator version

latest version

Steps to reproduce

new DefaultApi(
  new Configuration({
    basePath: "",
  }),
)

the basePath will replaced by "localhost/xxxx", but i expect it as /xxxx

Related issues/PRs

#2731

Suggest a fix

it caused by this line:

the code above assume that this.configuration.basePath not a empty string, otherwise it will be replaced by BASE_PATH.

use the below code to fix it:

return this.configuration.basePath != null ? this.configuration.basePath : BASE_PATH;

it means if this.configuration.basePath NOT A NULL OR UNDEFINED, then use it, otherwise use the BASE_PATH