code: @SuppressWarnings({"unchecked", "rawtypes"})
      protected void registerDependency(List additionalList, GrailsPlugin plugin) {
          if (!addedNames.contains(plugin.getName())) {
              addedNames.add(plugin.getName());
              additionalList.add(plugin);
              addPluginDependencies(additionalList, plugin);
          }
      }
docs: Adds a plugin to the additional if this hasn't happened already