code: @Override
      protected Collection<String> loadBundledPlugins() {
          // this is used in tests, when we want to override the default bundled plugins with .jpl (or .hpl) versions
          if (SystemProperties.getString("hudson.bundled.plugins") != null) {
              return Collections.emptySet();
          }
  
          try {
              return loadPluginsFromWar("/WEB-INF/plugins");
          } finally {
              loadDetachedPlugins();
          }
      }
docs: If the war file has any "/WEB-INF/plugins/*.jpi", extract them into the plugin directory.
  
  @return
  File names of the bundled plugins. Like {"ssh-slaves.jpi","subversion.jpi"}