PGPObjectFactory: Prevent ClassCastException when parsing dangling ModDetectionCodePacket

Author: vanitasvitae

pg/src/main/java/org/bouncycastle/openpgp/PGPObjectFactory.java

@@ -167,6 +167,8 @@ public Object nextObject()
             return new PGPMarker(in);
         case PacketTags.PADDING:
             return new PGPPadding(in);
+        case PacketTags.MOD_DETECTION_CODE:
+            return new UnknownPacket(PacketTags.MOD_DETECTION_CODE, in);
         }
 
         int tag = in.nextPacketTag();