code: public List<InvocationMarshaller<?>> getBootstrapServices (String[] bootGroups)
      {
          List<InvocationMarshaller<?>> services = Lists.newArrayList();
          for (String group : bootGroups) {
              services.addAll(_bootlists.get(group));
          }
          return services;
      }
docs: Constructs a list of all bootstrap services registered in any of the supplied groups.