Starting with a brand new installation of Eclipse and making a new WOLips project will immediately give you the following warnings in the lower central pane:

Chuck Hill provided the following solution:

"That is not an error, that is a warning. You can safely ignore it.
To make it go away:

Window - Preferences - Java - Compiler - Errors/Warnings - Potential
Programming Problems and see the top entry."

You'll have to do a rebuild after selecting to ignore "Serializable class without serialVersionUID:"

Voila, no more warnings.