Set keys = new HashSet();
Attributes existingMap = existingManifest.getMainAttributes();
Attributes newMap = manifest.getMainAttributes();
keys.addAll( existingMap.keySet() );
keys.addAll( newMap.keySet() );
for (Object key1 : keys) {
Attributes.Name key = (Attributes.Name) key1;
String newValue = (String) newMap.get(key);
String existingValue = (String) existingMap.get(key);
// special case classpath... they are equal when there entries