title: Error attempting to apply AttributeConverter
body: <p>I was using JPA <code>AttributeConverter</code> with spring boot 1.2.1 RELEASE and it worked fine. But I get the following error after upgrading to spring boot 1.3.0.RELEASE</p>
  
  <pre><code>    Caused by: javax.persistence.PersistenceException: Error attempting to apply AttributeConverter
      at org.hibernate.type.descriptor.converter.AttributeConverterSqlTypeDescriptorAdapter$1.bind(AttributeConverterSqlTypeDescriptorAdapter.java:103)
      at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:286)
      at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:281)
      at org.hibernate.type.AbstractSingleColumnStandardBasicType.nullSafeSet(AbstractSingleColumnStandardBasicType.java:56)
      at org.hibernate.persister.entity.AbstractEntityPersister.dehydrate(AbstractEntityPersister.java:2843)
      at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:3248)
      at org.hibernate.persister.entity.AbstractEntityPersister.updateOrInsert(AbstractEntityPersister.java:3183)
      at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:3525)
      at org.hibernate.action.internal.EntityUpdateAction.execute(EntityUpdateAction.java:159)
      at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:465)
      at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:351)
      at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:350)
      at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:56)
      at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1258)
      at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:425)
      at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.beforeTransactionCommit(JdbcTransaction.java:101)
      at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:177)
      at org.hibernate.jpa.internal.TransactionImpl.commit(TransactionImpl.java:77)
      at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:517)
      ... 81 more
  Caused by: java.lang.NullPointerException
      at rafito.spring.boot.domain.TimestampPersistenceConverter.convertToDatabaseColumn(TimestampPersistenceConverter.java:16)
      at rafito.spring.boot.domain.TimestampPersistenceConverter.convertToDatabaseColumn(TimestampPersistenceConverter.java:10)
      at org.hibernate.type.descriptor.converter.AttributeConverterSqlTypeDescriptorAdapter$1.bind(AttributeConverterSqlTypeDescriptorAdapter.java:97)
  </code></pre>
  
  <p>I am not setting serviceBeginTime and serviceEndTime in my POST JSON currently. But this wasn't giving me a null pointer before I upgraded spring boot version.</p>
  
  <p><strong>Converter class</strong></p>
  
  <pre><code>@Converter
  public class TimestampPersistenceConverter implements AttributeConverter&lt;Long, Timestamp&gt; {
  
  
      @Override
      public Timestamp convertToDatabaseColumn(Long aLong) {
          return new Timestamp(aLong);
      }
  
      @Override
      public Long convertToEntityAttribute(Timestamp timestamp) {
          return timestamp.getTime();
      }
  }
  </code></pre>
  
  <p><strong>Entity</strong></p>
  
  <pre><code>@Column(name = "service_begin_time")
  @Convert(converter = TimestampPersistenceConverter.class)
  Long serviceBeginTime;
  
  @Column(name = "service_end_time")
  @Convert(converter = TimestampPersistenceConverter.class)
  Long serviceEndTime;
  </code></pre>
  
  <p><strong>Database fields</strong></p>
  
  <pre><code>service_begin_time timestamp without time zone,
  service_end_time timestamp without time zone,
  </code></pre>