code: public static MessageTransformer createMessageTransformer(
              String className, SecorConfig config) throws Exception {
          Class<?> clazz = Class.forName(className);
          if (!MessageTransformer.class.isAssignableFrom(clazz)) {
              throw new IllegalArgumentException(String.format(
                      "The class '%s' is not assignable to '%s'.", className,
                      MessageTransformer.class.getName()));
          }
          return (MessageTransformer) clazz.getConstructor(SecorConfig.class)
                  .newInstance(config);
      }
docs: Create a MessageTransformer from it's fully qualified class name. The
  class passed in by name must be assignable to MessageTransformers and have
  1-parameter constructor accepting a SecorConfig. Allows the MessageTransformers
  to be pluggable by providing the class name of a desired MessageTransformers in
  config.
  
  See the secor.message.transformer.class config option.
  
  @param className class name
  @param config secor config
  @return MessageTransformer
  @throws Exception on error