{
assertEquals("%PDF-1.5", doc.getDocument().getHeaderString());
PDDocumentCatalog catalog = doc.getDocumentCatalog();
assertEquals("1.5", catalog.getVersion());
PDPage page = doc.getPage(0);
PDOptionalContentGroup ocg = (PDOptionalContentGroup)page.getResources()
.getProperties(COSName.getPDFName("MC0"));
assertNotNull(ocg);
assertEquals("background", ocg.getName());
assertNull(page.getResources().getProperties(COSName.getPDFName("inexistent")));
PDOptionalContentProperties ocgs = catalog.getOCProperties();
assertEquals(BaseState.ON, ocgs.getBaseState());
Set<String> names = new java.util.HashSet<String>(Arrays.asList(ocgs.getGroupNames()));
assertEquals(3, names.size());