Hi,

BuildWrapper contains an inner class Enviroment which extends
hudson.model.Environment (for some compatibility reason I suppose?). The setUp
method is required to return the inner class rather than
hudson.model.Environment, but is never used as anything but the latter. The
BuildWrapper.Environment is also not static, which forces it to be extended by
an inner class to a BuildWrapper, which is not very elegant (this connection to
BuildWrapper doesn't seem to be used in anyway either).

I understand that either change (return type, and/or static) will break binary
backwards compatibility, so this is pretty much low priority, wasn't sure which
of P1 and P5 is lower...

Actually, the return type should be compatible pretty much compatible if no one
is actually using the result of setUp() as BuildWrapper.Enviroment, but I'm not
100% sure of that.