code: public PluginLoader withExtensionPoints(Class... extensionPoints) {
          this.extensionPoints.addAll(
                  Stream.of(extensionPoints)
                          .distinct()
                          .collect(Collectors.<Class>toList())
          );
          return this;
      }
docs: Define extension points to be considered by this loader
  
  @param extensionPoints a list of extension point classes
  @return this