AnnotationHandlerCollector { public String getAnnotationHandler(String type, String handlerType) { if (type == null) { throw new NullPointerException("type"); } if (!handlers.containsKey(type)) { handlers.put(type, handlerType); } return handlers.get(type); } AnnotationHandlerCollector(Initializer initializer, Logger logger); boolean isModified(); String getAnnotationHandler(String type, String handlerType); void load(); void removeAnnotationHandler(String handler); @Override String toString(); String toList(); Map<String, String> handlers(); void fromList(String input);  }
@Test public void testGetAnnotationHandlerNull() { assertThrows(NullPointerException.class, () -> collector.getAnnotationHandler(null, null)); }