@Override
        protected boolean isOkToAdd(SendMessageRequest request) {
            return (requests.size() < config.getMaxBatchSize())
                    && ((request.getMessageBody().getBytes().length + batchSizeBytes) <= config.getMaxBatchSizeBytes());
        }
Processes the batch once closed. Is <em>NOT</em> called with a lock on {@code this}.
However, it's passed a local copy of both the {@code requests} and {@code futures} lists
made while holding the lock.
aws-java-sdk-sqs/src/main/java/com/amazonaws/services/sqs/buffered/SendQueueBuffer.java