code: private PluginDefinition pluginById(String id) {
          PluginDefinition def = pluginRegistry.get(id);
          
          if (def == null) {
              throw new PluginException(EXC_UNKNOWN_PLUGIN, null, null, id);
          }
          
          return def;
      }
docs: Lookup a plugin definition by its id. Raises a runtime exception if the plugin is not found.
  
  @param id Plugin id.
  @return The plugin definition.