withFileFromClasspath does not work for resources within a jar #213

  static Transferable fromClasspath(final String resourcePath) {
    URL resource = ClasspathTrait.class.getClassLoader()
        .getResource(resourcePath);

    try (InputStream stream = resource.openStream()) {
      byte[] bytes = IOUtils.toByteArray(stream);

      return new Transferable() {
        @Override
        public long getSize() {
          return bytes.length;
        }

        @Override
        public void transferTo(OutputStream outputStream) {
          try {
            IOUtils.write(bytes, outputStream);
          } catch (IOException e) {
            throw new RuntimeException(
                "Can't transfer resource " + resourcePath, e);
          }
        }
      };
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
  };