### Question:
ArgumentTypeRegistry { public static void deregisterArgumentType(Class<?> clazz) { if (clazz == null) { throw new NullPointerException("clazz"); } argTypeMap.remove(clazz); }  static ArgumentType<T> getArgumentType(PropertyDesc propertyDesc); static void registerArgumentType(Class<?> clazz,
            Class<? extends ArgumentType<?>> argumentTypeClass); static void deregisterArgumentType(Class<?> clazz); @SuppressWarnings("unchecked") static void registerCollectionArgumentType(
            Class<? extends Collection> collectionClass,
            Class<? extends CollectionType> argumentTypeClass); @SuppressWarnings("unchecked") static void deregisterCollectionArgumentType(
            Class<? extends Collection> collectionClass);  }### Answer:
@Test public void testDeregisterArgumentType() throws Exception { ArgumentTypeRegistry.deregisterArgumentType(String.class); ArgumentType<String> argumentType = ArgumentTypeRegistry .getArgumentType(String.class); assertNull(argumentType); }