ManagerComponentImpl implements ManagerComponent { @Override public <ENTITY> void put(Manager<ENTITY> manager) { requireNonNull(manager); managersByEntity.put(manager.getEntityClass(), manager); } ManagerComponentImpl(); @Override void put(Manager<ENTITY> manager); @Override @SuppressWarnings("unchecked") Manager<E> managerOf(Class<E> entityClass); @Override Stream<Manager<?>> stream();  }
@Test void put() { assertThrows(NullPointerException.class, () -> instance.put(null)); }