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


    // given
    
    Reference ref1 = createReference(1, "X");
    List<Reference> refs = Lists.newArrayList(ref1);
    Tuple2<String, Iterable<Reference>> srcDocIdReferences = new Tuple2<>(null, refs);
    
    
    // execute
    
    referenceToPicOutConverter.convertToPicOut(srcDocIdReferences);
}