title: Unresolveable build extension in Maven
body: <p>I am getting below error while building maven project.</p>
  
  <pre><code>  [INFO] Scanning for projects...
      Downloading: http://repo.jfrog.org/artifactory/plugins-releases-local/org/jfrog/maven/annomo
      jo/maven-plugin-tools-anno/1.4.0/maven-plugin-tools-anno-1.4.0.pom
      [ERROR] [ERROR] Some problems were encountered while processing the POMs:
      [ERROR] Unresolveable build extension: Plugin org.mule.tools.maven:mule-app-maven-plugin:1.0
       or one of its dependencies could not be resolved: Failed to collect dependencies at org.mul
      e.tools.maven:mule-app-maven-plugin:jar:1.0 -&gt; org.jfrog.maven.annomojo:maven-plugin-tools-a
      nno:jar:1.4.0 @
      [ERROR] Unknown packaging: mule @ line 6, column 13
       @
      [ERROR] The build could not read 1 project -&gt; [Help 1]
      [ERROR]
      [ERROR]   The project com.test:testproj:1.0.1 (C:\Users\john\proj\testproj
      c\pom.xml) has 2 errors
      [ERROR]     Unresolveable build extension: Plugin org.mule.tools.maven:mule-app-maven-plugin
      :1.0 or one of its dependencies could not be resolved: Failed to collect dependencies at org
      .mule.tools.maven:mule-app-maven-plugin:jar:1.0 -&gt; org.jfrog.maven.annomojo:maven-plugin-too
      ls-anno:jar:1.4.0: Failed to read artifact descriptor for org.jfrog.maven.annomojo:maven-plu
      gin-tools-anno:jar:1.4.0: Could not transfer artifact org.jfrog.maven.annomojo:maven-plugin-
      tools-anno:pom:1.4.0 from/to jfrog (http://repo.jfrog.org/artifactory/plugins-releases-local
      ): Connect to repo.jfrog.org:80 [repo.jfrog.org/52.200.110.120, repo.jfrog.org/52.73.83.233]
       failed: Connection refused: connect -&gt; [Help 2]
      [ERROR]     Unknown packaging: mule @ line 6, column 13
      [ERROR]
      [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
      [ERROR] Re-run Maven using the -X switch to enable full debug logging.
      [ERROR]
      [ERROR] For more information about the errors and possible solutions, please read the follow
      ing articles:
      [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/ProjectBuildingException
      [ERROR] [Help 2] http://cwiki.apache.org/confluence/display/MAVEN/PluginManagerException
  </code></pre>
  
  <p>Earlier we got connection refused for different IP. we opened the firewall for the same. Now it is showing differnt IP for connection refused. 
  Could you please help us on this to reslove the issue?</p>