Invoke equals on a PdfName constant rather than on a nullable object

DEVSIX-5631

Author: ars18wrw

kernel/src/main/java/com/itextpdf/kernel/pdf/PdfPage.java

@@ -402,7 +402,7 @@ public PdfPage copyTo(PdfDocument toDocument, IPdfPageExtraCopier copier) {
         PdfPage page = getDocument().getPageFactory().createPdfPage(dictionary);
         copyInheritedProperties(page, toDocument);
         for (PdfAnnotation annot : getAnnotations()) {
-            if (annot.getSubtype().equals(PdfName.Link)) {
+            if (PdfName.Link.equals(annot.getSubtype())) {
                 getDocument().storeLinkAnnotation(page, (PdfLinkAnnotation) annot);
             } else {
                 PdfAnnotation newAnnot = PdfAnnotation.makeAnnotation(

kernel/src/test/java/com/itextpdf/kernel/pdf/PdfPagesTest.java

@@ -44,11 +44,13 @@ This file is part of the iText (R) project.
 
 import com.itextpdf.io.LogMessageConstant;
 import com.itextpdf.io.image.ImageDataFactory;
+import com.itextpdf.io.source.RandomAccessSourceFactory;
 import com.itextpdf.io.util.MessageFormatUtil;
 import com.itextpdf.kernel.PdfException;
 import com.itextpdf.kernel.colors.ColorConstants;
 import com.itextpdf.kernel.geom.PageSize;
 import com.itextpdf.kernel.geom.Rectangle;
+import com.itextpdf.kernel.pdf.annot.PdfAnnotation;
 import com.itextpdf.kernel.pdf.canvas.PdfCanvas;
 import com.itextpdf.kernel.pdf.extgstate.PdfExtGState;
 import com.itextpdf.kernel.pdf.xobject.PdfFormXObject;
@@ -586,6 +588,26 @@ public void verifyPagesAreNotReadOnOpenTest() throws IOException {
         Assert.assertFalse(reader.pagesAreRead);
     }
 
+    @Test
+    public void copyAnnotationWithoutSubtypeTest() throws IOException {
+        try (
+                ByteArrayOutputStream baos = createSourceDocumentWithEmptyAnnotation(new ByteArrayOutputStream());
+                PdfDocument documentToMerge = new PdfDocument(
+                        new PdfReader(
+                                new RandomAccessSourceFactory().createSource(baos.toByteArray()),
+                                new ReaderProperties()));
+                ByteArrayOutputStream resultantBaos = new ByteArrayOutputStream();
+                PdfDocument resultantDocument = new PdfDocument(new PdfWriter(resultantBaos))) {
+
+            // We do expect that the following line will not throw any NPE
+            PdfPage copiedPage = documentToMerge.getPage(1).copyTo(resultantDocument);
+            Assert.assertEquals(1, copiedPage.getAnnotations().size());
+            Assert.assertNull(copiedPage.getAnnotations().get(0).getSubtype());
+
+            resultantDocument.addPage(copiedPage);
+        }
+    }
+
     @Test
     public void readPagesInBlocksTest() throws IOException {
         String srcFile = sourceFolder + "docWithBalancedPageTree.pdf";
@@ -735,6 +757,15 @@ private static int verifyIntegrity(PdfPagesTree pagesTree) {
         return -1;
     }
 
+    private static ByteArrayOutputStream createSourceDocumentWithEmptyAnnotation(ByteArrayOutputStream baos) {
+        try (PdfDocument sourceDocument = new PdfDocument(new PdfWriter(baos))) {
+            PdfPage page = sourceDocument.addNewPage();
+            PdfAnnotation annotation = PdfAnnotation.makeAnnotation(new PdfDictionary());
+            page.addAnnotation(annotation);
+            return baos;
+        }
+    }
+
     private class CustomPdfReader extends PdfReader {
 
         public boolean pagesAreRead = false;