swap method body of onError and handleError

Author: Fred1155

services/s3/src/main/java/software/amazon/awssdk/services/s3/internal/multipart/MultipartDownloaderSubscriber.java

@@ -185,18 +185,18 @@ private void requestMoreIfNeeded(GetObjectResponse response) {
      * The method used by the Subscriber itself when error occured.
      */
     private void handleError(Throwable t) {
-        onError(t);
-    }
-
-    @Override
-    public void onError(Throwable t) {
         CompletableFuture<GetObjectResponse> partFuture;
         while ((partFuture = getObjectFutures.poll()) != null) {
             partFuture.cancel(true);
         }
         future.completeExceptionally(t);
     }
 
+    @Override
+    public void onError(Throwable t) {
+        handleError(t);
+    }
+
     @Override
     public void onComplete() {
         future.complete(null);