PDFBOX-6026: output transformed xmp if something goes wrong

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1926837 13f79535-47bb-0310-9956-ffa450edef68

Author: THausherr

xmpbox/src/test/java/org/apache/xmpbox/parser/DeserializationTest.java

@@ -403,6 +403,6 @@ private void checkTransform(XMPMetadata metadata, String expected)
         byte[] ba = replaced.getBytes(StandardCharsets.UTF_8);
         byte[] digest = MessageDigest.getInstance("SHA-256").digest(ba);
         String result = new BigInteger(1, digest).toString();
-        assertEquals(expected, result);
+        assertEquals(expected, result, "output:\n" + replaced);
     }
 }