code: public static Action resourceContent(final String resourcePath) {
          return new Action(input -> {
              final HttpResponsePacket responsePacket = input.getResponse();
              String encoding = responsePacket == null ? input.getCharacterEncoding() : responsePacket.getCharacterEncoding();
              return resourceContent(resourcePath, encoding).apply(input);
          });
      }
docs: Writes content and content-type of resource file to response.
  Tries to detect content type based on file extension. If can not detect - content-type is not set.
  For now there are following bindings:
  <ul>
  <li>.xml - `application/xml`</li>
  <li>.json - `application/xml`</li>
  </ul>