DVCS plugin is not able to connect to github.com if it runs behind a forward proxy with basic authentication enabled

Summary

JIRA DVCS plugin fails to connect to github.com if JIRA is accessing public internet through a forward proxy that uses basic authentication.

Environment

• JIRA Software with DVCS plugin
• Configure a forward proxy using basic proxy authentication: eg: squid or apache
• Configure JIRA to use a forward proxy using following start up options:

  -Dhttp.proxyHost=127.0.0.1 -Dhttp.proxyPort=3128 -Dhttp.proxyUser=user -Dhttp.proxyPassword=pass -Dhttps.proxyHost=127.0.0.1 -Dhttps.proxyPort=3128 -Dhttps.proxyUser=user -Dhttps.proxyPassword=pass  -Djdk.http.auth.tunneling.disabledSchemes
  

Steps to Reproduce

1. After a freshly restarted JIRA
2. Login to JIRA as admin
3. Go to Applications and try to configure DVCS to connect to github

Expected Results

• JIRA is able to connect to github and verify the user account.

Actual Results

• JIRA fails to connect to github and user is faced with a connection/access error.
• In the logs we see warnings like this:

  2018-05-24 11:27:15,178 http-nio2-13032-exec-44 WARN admin 687x111223x1 1q8lhhh IP,IP,IP /secure/admin/AddGithubOrganization!finish.jspa [c.a.j.p.d.s.github.webwork.AddGithubOrganization] Caused by: Unable to tunnel through proxy. Proxy returns "HTTP/1.1 407 Proxy Authentication Required"
  

• Jira doesn't send authenticaion header to proxy, this header is missing:

  Proxy-authorization: Basic dXNlcjp1c2Vy
  

Notes

Please check the related bug for JIRA Core: JRASERVER-67487

Workaround

Please check the related bug for JIRA Core: JRASERVER-67487