title: Maven:unable to find valid certification path to requested target
body: <p>I get this error when I try to <code>mvn clean install</code> <a href="https://github.com/eclipse/che-lib/tree/5.22.0/che-orion-editor" rel="nofollow noreferrer">che-orion-editor</a>，the version is 5.22.0.</p>
  
  <blockquote>
    <p>Plugin org.apache.maven.plugins:maven-patch-plugin:1.1.1 or one of its dependencies could not be resolved: Failed to read artifact descriptor for org.apache.maven.plugins:maven-patch-plugin:jar:1.1.1: Could not transfer artifact org.apache.maven.plugins:maven-patch-plugin:pom:1.1.1 from/to codenvy-public-repo (<a href="https://maven.codenvycorp.com/content/groups/public/" rel="nofollow noreferrer">https://maven.codenvycorp.com/content/groups/public/</a>): sun.security.validator.ValidatorException: <code>PKIX path building failed</code>: sun.security.provider.certpath.SunCertPathBuilderException: <code>unable to find valid certification path to requested target</code> -> [Help 1]</p>
  </blockquote>
  
  <p>I have set the maven proxy correctly.</p>
  
  <p>And I have tried <a href="https://stackoverflow.com/questions/25911623/problems-using-maven-and-ssl-behind-proxy">this</a>, it doen't work.</p>