But, I think if you did ask there,
you'd learn that Tycho does not support the old-style "site.xml"
repositories, which is what the "findbugs" repo is, that you
referenced. p2 by itself (or tools that delegate completely to p2, such
aggregator) do handle these old-style
sites, by basically "downloading everything" and doing a "conversion
to new-style site" on the fly.
You would probably also learn, if you
asked on tycho-users, that your options are to a) convince original project
(findbugs) to "move up", or b) make your own p2 repo "on
the side" from the old-style site, and then in your build point to
your new-style site. At least, that's what I learned by doing a web search
for "Tycho and site.xml" and finding
12/26/2014 12:01 PM
ClassCastException in LocalMetadataRepository
I am one of the maintainers of m2e-code-quality . When I add the FindBugs
update site  as a p2 repository, the build fails .
Debugging into the problem I found that the problem is
LocalMetadataRepository:325 . It's actually RemoteMetadataRepositoryManager
not a MetadataRepositoryManager. Therefore resolving the update site fails.
Am I doing something wrong? Or might this be a bug?