### Question:
PersistenceDelegator { public void remove(Object e) { if (e == null) { throw new IllegalArgumentException("Entity to be removed must not be null."); } EntityMetadata metadata = getMetadata(e.getClass()); ObjectGraph graph = new GraphGenerator().generateGraph(e, this, new ManagedState()); Node node = graph.getHeadNode(); try { lock.writeLock().lock(); node.setPersistenceDelegator(this); node.remove(); flushManager.buildFlushStack(node, EventType.DELETE); flush(); } finally { lock.writeLock().unlock(); } graph.clear(); graph = null; if (log.isDebugEnabled()) { log.debug("Data removed successfully for entity : " + e.getClass()); } } PersistenceDelegator(final KunderaMetadata kunderaMetadata, final PersistenceCache pc); void persist(Object e); E findById(final Class<E> entityClass, final Object primaryKey); List<E> find(Class<E> entityClass, Object... primaryKeys); List<E> find(Class<E> entityClass, Map<String, String> embeddedColumnMap); void remove(Object e); E merge(E e); void detach(Object entity); Client getClient(EntityMetadata m); Client getClient(final String persistenceUnit); EntityEventDispatcher getEventDispatcher(); boolean isOpen(); void refresh(Object entity); boolean isTransactionInProgress(); PersistenceCache getPersistenceCache(); KunderaMetadata getKunderaMetadata();  }### Answer:
@Test public void testRemove() { PersonnelDTO paramObject = new PersonnelDTO(); PersonnelDTO dto = new PersonnelDTO(); dto.setPersonId("123"); em.persist(dto); dto = em.find(PersonnelDTO.class, 123); try { em.remove(null); } catch (KunderaException e) { Assert.assertEquals("java.lang.IllegalArgumentException: Entity to be removed must not be null.", e.getMessage()); } em.remove(dto); dto = em.find(PersonnelDTO.class, "123"); Assert.assertNull(dto); try { em.remove(paramObject); } catch (Exception e) { Assert.assertEquals("123", "123"); } }