Check copied outline's destination on null reference. Add a test.

DEVSIX-1660

Autoported commit.
Original commit hash: [f2eea8ee7]

Author: ars18wrw

itext.tests/itext.kernel.tests/itext/kernel/utils/PdfMergerTest.cs

@@ -90,6 +90,26 @@ public virtual void MergeDocumentTest01() {
             }
         }
 
+        /// <exception cref="System.IO.IOException"/>
+        /// <exception cref="System.Exception"/>
+        [NUnit.Framework.Test]
+        [LogMessage(iText.IO.LogMessageConstant.SOURCE_DOCUMENT_HAS_ACROFORM_DICTIONARY)]
+        public virtual void MergeDocumentOutlinesWithNullDestinationTest01() {
+            String resultFile = destinationFolder + "mergeDocumentOutlinesWithNullDestinationTest01.pdf";
+            String filename = sourceFolder + "null_dest_outline.pdf";
+            PdfDocument sourceDocument = new PdfDocument(new PdfReader(filename));
+            PdfMerger resultDocument = new PdfMerger(new PdfDocument(new PdfWriter(resultFile)));
+            resultDocument.Merge(sourceDocument, 1, 1);
+            resultDocument.Close();
+            sourceDocument.Close();
+            CompareTool compareTool = new CompareTool();
+            String errorMessage = compareTool.CompareByContent(resultFile, sourceFolder + "cmp_mergeDocumentOutlinesWithNullDestinationTest01.pdf"
+                , destinationFolder, "diff_");
+            if (errorMessage != null) {
+                NUnit.Framework.Assert.Fail(errorMessage);
+            }
+        }
+
         /// <exception cref="System.IO.IOException"/>
         /// <exception cref="System.Exception"/>
         [NUnit.Framework.Test]

itext.tests/itext.kernel.tests/resources/itext/kernel/utils/PdfMergerTest/cmp_mergeDocumentOutlinesWithNullDestinationTest01.pdf

@@ -2111,8 +2111,11 @@ private void CloneOutlines(ICollection<PdfOutline> outlinesToCopy, PdfOutline ne
             }
             foreach (PdfOutline outline in oldParent.GetAllChildren()) {
                 if (outlinesToCopy.Contains(outline)) {
-                    PdfObject destObjToCopy = outline.GetDestination().GetPdfObject();
-                    PdfDestination copiedDest = GetCatalog().CopyDestination(destObjToCopy, page2page, toDocument);
+                    PdfDestination copiedDest = null;
+                    if (null != outline.GetDestination()) {
+                        PdfObject destObjToCopy = outline.GetDestination().GetPdfObject();
+                        copiedDest = GetCatalog().CopyDestination(destObjToCopy, page2page, toDocument);
+                    }
                     PdfOutline child = newParent.AddOutline(outline.GetTitle());
                     if (copiedDest != null) {
                         child.AddDestination(copiedDest);

itext.tests/itext.kernel.tests/resources/itext/kernel/utils/PdfMergerTest/null_dest_outline.pdf

@@ -1 +1 @@
-0d625679cd2f5be0c7fc50d62a423267b7244f4f
+f2eea8ee75c83026cba91bb84d1833c59d08bcf0