@Test(expected = ConfigException.class)
  public void testLoadConfigWithoutLoader() {
    Map<String, String> config = new HashMap<>();
    config.put(JobConfig.JOB_NAME, "new-test-job");

    ConfigUtil.loadConfig(new MapConfig(config));
  }
This fails because Util will interpret the empty string value as a single rewriter which has the empty string as a
name, and there is no rewriter class config for a rewriter name which is the empty string.
TODO: should this be fixed to interpret the empty string as an empty list?
samza-core/src/test/java/org/apache/samza/util/TestConfigUtil.java