Make CompareTool compare page dictionaries as usual dictionaries if both cmp and out page dicts are not in the doc's page trees

DEVSIX-2137

Author: yulian-gaponenko

kernel/src/main/java/com/itextpdf/kernel/utils/CompareTool.java

@@ -1411,12 +1411,19 @@ private boolean compareObjects(PdfObject outObj, PdfObject cmpObj, ObjectPath cu
                     outPagesRef.add(outRefKey.getDocument().getPage(i).getPdfObject().getIndirectReference());
                 }
             }
-            if (cmpPagesRef.contains(cmpRefKey) && cmpPagesRef.indexOf(cmpRefKey) == outPagesRef.indexOf(outRefKey))
-                return true;
-            if (compareResult != null && currentPath != null)
-                compareResult.addError(currentPath, MessageFormatUtil.format("The dictionaries refer to different pages. Expected page number: {0}. Found: {1}",
-                        cmpPagesRef.indexOf(cmpRefKey) + 1, outPagesRef.indexOf(outRefKey)) + 1);
-            return false;
+
+            // If at least on of the page dictionaries is in the document's page tree, we don't proceed with deep comparison,
+            // because pages are compared at different level, so we compare only their index.
+            // However only if both page dictionaries are not in the document's page trees, we continue to comparing them as normal dictionaries.
+            if (cmpPagesRef.contains(cmpRefKey) || outPagesRef.contains(outRefKey)) {
+                if (cmpPagesRef.contains(cmpRefKey) && cmpPagesRef.indexOf(cmpRefKey) == outPagesRef.indexOf(outRefKey)) {
+                    return true;
+                }
+                if (compareResult != null && currentPath != null)
+                    compareResult.addError(currentPath, MessageFormatUtil.format("The dictionaries refer to different pages. Expected page number: {0}. Found: {1}",
+                            cmpPagesRef.indexOf(cmpRefKey) + 1, outPagesRef.indexOf(outRefKey) + 1));
+                return false;
+            }
         }
 
         if (cmpDirectObj.isDictionary()) {