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


    // given
    
    Tuple2<String, Iterable<Reference>> srcDocIdReferences = new Tuple2<>("XYZ", null);
    
    
    // execute
    
    referenceToPicOutConverter.convertToPicOut(srcDocIdReferences);
}