public String render(File templateFile) throws IOException {
    String template = FileUtils.readFileToString(templateFile, Charset.defaultCharset());
    return render(template);
  }
@Test
  void testRender() {
    // given template variables
    K8sSpecTemplate template = new K8sSpecTemplate();
    template.put("name", "world");

    // when
    String spec = template.render("Hello {{name}}");

    // then
    assertEquals("Hello world", spec);
  }