@Test(expectedExceptions=NullPointerException.class)
public void convertToReference_NULL_idWithSimilarity() {

    
    // given
    
    MatchableEntity entity = Mockito.mock(MatchableEntity.class);
    Tuple2<MatchableEntity, IdWithSimilarity> entityWithId = new Tuple2<>(entity, null);
    
    // execute
    
    matchableEntityWithSimilarityConverter.convertToReference(entityWithId);
    
}