List all installed Jenkins Extension

jenkins-list-extension.groovy

import jenkins.model.*;
import hudson.ExtensionFinder;

List<ExtensionFinder> finders = Jenkins.instance.getExtensionList(ExtensionFinder.class);

for (finder in finders) {
  println(">>> " + finder);
  if (finder instanceof hudson.ExtensionFinder.GuiceFinder) {
    println(finder.annotations.size());
    for (key in finder.annotations.keySet()) {
       println(key);
    }
  } else if (finder instanceof hudson.cli.declarative.CLIRegisterer) {
    println(finder.discover(Jenkins.instance));
    for (extension in finder.discover(Jenkins.instance)) {
      println("CLI wrapper for " + extension.instance.class);
      // not sure what to do with those      
    }
  } else {
    println("UNKNOWN FINDER TYPE"); 
  }  
}