@Test
public void testExecute() throws Exception {

    Map<String, Object> fieldsAndValues = new HashMap<>();
    fieldsAndValues.put("1", "one");
    fieldsAndValues.put("2", "two");
    Map<String, String> defaults = new HashMap<>();
    defaults.put("2", "TWO");
    defaults.put("3", "THREE");
    StreamlineEvent event = StreamlineEventImpl.builder().fieldsAndValues(fieldsAndValues).dataSourceId("dsrcid").build();
    TransformRuntime transformRuntime = new MergeTransformRuntime(new MergeTransform(defaults));
    List<StreamlineEvent> result = transformRuntime.execute(event);
    System.out.println(result);
    assertEquals(1, result.size());
    assertEquals("two", result.get(0).get("2"));
    assertEquals("THREE", result.get(0).get("3"));
}