title: Maven-gae-plugin 0.9.4: no version available for org.codehaus.plexus:plexus-archiver:jar-- Help me explain the solution of the bug
body: <p>This bug was closed on github, 
  <a href="https://github.com/maven-gae-plugin/maven-gae-plugin/issues/39" rel="nofollow">https://github.com/maven-gae-plugin/maven-gae-plugin/issues/39</a>
  however i don't understand its fixing, and when i execute gae goal such as mvn gae:update it always gives me the same problem. could anyone explain the root cause of this problem based on its fixing?</p>
  
  <p>For your info, i copy-paste the original problem and its fixing here:</p>
  
  <blockquote>
    <blockquote>
      <p>From this morning I continue to get this error:</p>
    </blockquote>
    
    <p>Failed to execute goal net.kindleit:maven-gae-plugin:0.9.4:unpack
    (execution2) on project gui: Execution execution2 of goal
    net.kindleit:maven-gae-plugin:0.9.4:unpack failed: Plugin
    net.kindleit:maven-gae-plugin:0.9.4 or one of its dependencies could
    not be resolved: Failed to collect dependencies for
    net.kindleit:maven-gae-plugin:jar:0.9.4 (): No versions available for
    org.codehaus.plexus:plexus-archiver:jar:[1.2,3.0) within specified
    range</p>
    
    <p>.. and I am stuck with this plugin at the moment!</p>
  </blockquote>
  
  <p>the fix is:</p>
  
  <blockquote>
    <p>.. and I added the "-U" option to the command I use to use: mvn clean
    verify .. it becomes: mvn -U clean verify</p>
  </blockquote>
  
  <p>Thanks in advance.</p>