@Test
public void verifyAggregateDataValuesOnExistingPSI_PayloadHasNoDataValues()
{

    Event event1 = new Event();
    event1.setUid( CodeGenerator.generateUid() );
    event1.setDataValues( Sets.newHashSet() );
    Map<String, ProgramStageInstance> programStageInstanceMap = new HashMap<>();
    programStageInstanceMap.put( event1.getUid(), createPsi( event1.getUid(),
        createEventDataValue( "abcd", "val1" ),
        createEventDataValue( "efgh", "val2" ),
        createEventDataValue( "ilmn", "val3" ) ) );
    
    Map<String, Set<EventDataValue>> dataValues = subject.aggregateDataValues( Lists.newArrayList( event1 ),
        programStageInstanceMap, importOptions );
    
    assertThat( dataValues, is( notNullValue() ) );
    assertThat( dataValues.keySet(), hasSize( 1 ) );
    assertThat( dataValues.get( event1.getUid() ), hasSize( 0 ) );
}