Improve unwoven class file handling in SimpleCache

Also update lib/aspectj/aspectjweaver.jar to fix integration tests.

Fixes #285.

Co-authored-by: Kimming Lau <294001791@qq.com>
Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

weaver/src/main/java/org/aspectj/weaver/tools/cache/SimpleCache.java

@@ -72,8 +72,7 @@ public class SimpleCache {
 		byte[] res = get(classname, bytes);
 
 		if (Arrays.equals(SAME_BYTES, res)) {
-			// TODO: Should we return null (means "not transformed") in this case?
-			return bytes;
+			return null;
 		} else {
 			if (res != null) {
 				initializeClass(classname, res, loader, protectionDomain);
@@ -97,7 +96,7 @@ public class SimpleCache {
 
 		String key = generateKey(classname, origbytes);
 
-		if (Arrays.equals(origbytes, wovenbytes)) {
+		if (wovenbytes == null || Arrays.equals(origbytes, wovenbytes)) {
 			cacheMap.put(key, SAME_BYTES);
 			return;
 		}