### Question:
ReferenceAttributeConverter implements AttributeConverter<Reference, String> { @Override public String convertToDatabaseColumn( Reference attribute ) { return (attribute == null) ? null : (attribute.getType() + SEPARATOR + attribute.getValue()); }  @Override String convertToDatabaseColumn( Reference attribute ); @Override Reference convertToEntityAttribute( String dbData ); static final String SEPARATOR; }### Answer:
@Test public void convertToDatabaseColumnNull() { Assert.assertNull( converter.convertToDatabaseColumn( null ) ); }
@Test public void convertToDatabaseColumn() { Assert.assertEquals( "CODE:678", converter.convertToDatabaseColumn( new Reference( "678", ReferenceType.CODE ) ) ); }