title: How to add Github raw repositories to Sonatype Nexus as Proxy repository?
body: <p>Nowadays there are a lot of github hosted Maven repositories. 
  ex) <a href="https://github.com/nhnopensource/nhnopensource.maven.repo" rel="noreferrer">https://github.com/nhnopensource/nhnopensource.maven.repo</a></p>
  
  <p>I tried to add those repositories into my Sonatype Nexus repository manager as proxy repository, but failed all the time.</p>
  
  <p>But the repositories work fine when I set repository url directly to the github repositories in gradle/maven configuration.</p>
  
  <p>Has anybody succeeded to add github hosted maven repository into Nexus?</p>