public long getBytes() {
        return bytes;
    }
Returns the number of bytes associated with the event. The number of
bytes are not necessarily the same as the number of bytes transferred,
and it's meaning depends on the specific event type. For example, the
bytes of a {@link ProgressEventType#REQUEST_CONTENT_LENGTH_EVENT} refers
to the expected number of bytes to be sent to AWS, not the actual number
of bytes that have been transferred.
aws-java-sdk-core/src/main/java/com/amazonaws/event/ProgressEvent.java