In this line:

  https://github.com/jenkinsci/pipeline-githubnotify-step-plugin/blob/d88d474e93d96a264b82baa984be2a1096e92016/src/main/java/org/jenkinsci/plugins/pipeline/githubstatusnotification/GitHubStatusNotificationStep.java#L223

CREDENTIALS_ID_NOT_EXISTS is returned, even when the credentials do exist but are not of the right type (UsernamePasswordCredentials.class). It would be great if the plugin could give an explicit error when the credentials do exist but are of the wrong type (this cost me a couple hours debugging, having accidentally used a "Password" credential).

Thanks!