static String getContextPath(Props props) {
    String context = props.value(WEB_CONTEXT.getKey(), "");
    if ("/".equals(context)) {
      context = "";
    } else if (!"".equals(context) && context != null && !context.startsWith("/")) {
      throw MessageException.of(format("Value of '%s' must start with a forward slash: '%s'", WEB_CONTEXT.getKey(), context));
    }
    return context;
  }
@Test
  public void root_context_path_must_be_blank() {
    props.setProperty("sonar.web.context", "/");

    assertThat(TomcatContexts.getContextPath(new Props(props))).isEmpty();
  }