@Test
public void keepAll() {

    for (PDPage current : document.getPages()) {
        mapping.addLookupEntry(current, new PDPage());
    }
    PDDocumentOutline outline = new PDDocumentOutline();
    new OutlineDistiller(document).appendRelevantOutlineTo(outline, mapping);
    assertTrue(outline.hasChildren());
    assertEquals(5, outline.getOpenCount());
}