jenkins auth with Chinese Character failed

error is as follows:
Exception in thread "main" org.apache.http.client.HttpResponseException: Invalid password/token for user: ???

I check the source code, the jenkins http client use ascii as default charset when using basic auth, I think it should be modified to use more conveniently.

Start at the Jenkins HTTP client's basic-auth handling and inspect how the username and password are encoded before the request is sent. Reproduce the failure with Chinese-character credentials, then add coverage showing that non-ASCII authentication succeeds without changing existing ASCII behavior.

索引モデルが issue の本文から書いたものです。