@Test
public void testDefaultKeyValue() throws ClassNotFoundException,
    InstantiationException, IllegalAccessException {

  Interceptor.Builder builder = InterceptorBuilderFactory.newInstance(
      InterceptorType.STATIC.toString());
  builder.configure(new Context());
  Interceptor interceptor = builder.build();
  Event event = EventBuilder.withBody("test", Charsets.UTF_8);
  Assert.assertNull(event.getHeaders().get(Constants.KEY));
  event = interceptor.intercept(event);
  String val = event.getHeaders().get(Constants.KEY);
  Assert.assertNotNull(val);
  Assert.assertEquals(Constants.VALUE, val);
}