Script to go inside folders

gistfile1.txt

goInsideFolder(Jenkins.instance.items)

public void goInsideFolder(List<TopLevelItem> items) {
  for ( TopLevelItem item : items) {
    if (item instanceof com.cloudbees.hudson.plugins.folder.Folder) {
      goInsideFolder(item.getItems());
    }
    else { 
      println item.fullName;
    }
  }
}