docs: public static void initializeFilterMap(final TSDB tsdb) 
        throws ClassNotFoundException, NoSuchMethodException, NoSuchFieldException, 
        IllegalArgumentException, SecurityException, IllegalAccessException, 
        InvocationTargetException {
      final List<TagVFilter> filter_plugins = 
          PluginLoader.loadPlugins(TagVFilter.class);
      if (filter_plugins != null) {
        for (final TagVFilter filter : filter_plugins) {
          // validate required fields and methods
          filter.getClass().getDeclaredMethod("description");
          filter.getClass().getDeclaredMethod("examples");
          filter.getClass().getDeclaredField("FILTER_NAME");
          
          final Method initialize = filter.getClass()
              .getDeclaredMethod("initialize", TSDB.class);
          initialize.invoke(null, tsdb);
          
          final Constructor<? extends TagVFilter> ctor = 
              filter.getClass().getDeclaredConstructor(String.class, String.class);
          
          final Pair<Class<?>, Constructor<? extends TagVFilter>> existing = 
              tagv_filter_map.get(filter.getType());
          if (existing != null) {
            LOG.warn("Overloading existing filter " + 
                existing.getClass().getCanonicalName() + 
                " with new filter " + filter.getClass().getCanonicalName());
          }
          tagv_filter_map.put(filter.getType().toLowerCase(), 
              new Pair<Class<?>, Constructor<? extends TagVFilter>>(
                  filter.getClass(), ctor));
          LOG.info("Successfully loaded TagVFilter plugin: " + 
              filter.getClass().getCanonicalName());
        }
        LOG.info("Loaded " + tagv_filter_map.size() + " filters");
      }
    }