AWS client code. Ah, yes, the "dispatch async error handler then throw the exception anyway" pattern.

silly.java

public Future<DeleteMessageBatchResult> deleteMessageBatchAsync(
            final DeleteMessageBatchRequest deleteMessageBatchRequest,
            final AsyncHandler<DeleteMessageBatchRequest, DeleteMessageBatchResult> asyncHandler)
                    throws AmazonServiceException, AmazonClientException {
        return executorService.submit(new Callable<DeleteMessageBatchResult>() {
            public DeleteMessageBatchResult call() throws Exception {
              DeleteMessageBatchResult result;
                try {
                result = deleteMessageBatch(deleteMessageBatchRequest);
              } catch (Exception ex) {
                  asyncHandler.onError(ex);
            throw ex;
              }
              asyncHandler.onSuccess(deleteMessageBatchRequest, result);
                 return result;
        }
    });