Just to dig into this a bit further, because let's face it, having to refactor/rename something temporarily is not an elegant solution, in my second dev environment where I experienced the same issue I found that the "Automatically Build" option (under the Projects menu) was enabled. If I disable this option, and either Clean or Build Project again, the XFCP classes are resolved.
Must be something weird (or that I don't fully understand) about Eclipse's "Automatically Build" option.