There can be 2 possibilities.
- You have experinced connection problems to central repository.
- Something is wrong in your pom.xml
The exception says that the problem is not in YCSB but in connection to repository while trying to download maven clean plugin.
So, send here pom.xml and just in case check you network connection and try again. Is there a chance that you access internet via browser using proxy while maven does it directly, so the connection is unavailable? Or firewall in your company checks user-agent and does not allow you to connect to repository?
EDIT:
BTW it seems that version 2.4.1 is not in the repository. At least manually I can see version 1.0, 1.0 beta and 1.5