[Java][Webclient] Authentication queryParams double encoded

Created by: marcoreni

Description

A querystring authentication param is double encoded during request.

openapi-generator version

3.2.3-SNAPSHOT

OpenAPI declaration file content or url

security:
  - apiKey: []
components:
  securitySchemes:
    apiKey:
      type: apiKey
      in: query
      name: apiKey
[...]

Steps to reproduce

1. Generate a client with authentication
2. Set 1234= as auth value
3. Request should be sent as apiKey=1234%3D, but instead is sent as apiKey=1234%253D

Suggest a fix/enhancement

I'm assuming that this behavior happens for all query params, since there is no special handling for authentication query params once these are added to the list in https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/Java/libraries/webclient/ApiClient.mustache#L529 .

I checked the generated code and debugged a request.

1. During prepareRequest() all queryParams are encoded.
2. During builder.build().toUri() (specifically during toUri()) the params are encoded once again, since build() is called without encoded param (see https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/util/UriComponentsBuilder.html#build-- / https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/util/UriComponentsBuilder.html#build-boolean- ).

I think the best solution would be to leave the encoding to toUri(), thus removing the loop in prepareRequest() (https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/Java/libraries/webclient/ApiClient.mustache#L534).