Hi there,
it seems I just ran into
https://issues.sonatype.org/browse/NEXUS-6622
. It looks like the vaadin maven repos deliver an incorrect Content-Type header for its artifacts. The Content-Type contains an invalid charset=binary.
Though there is fix for Nexus available, I’m wondering whether this issue could be fixed on your side.
What surprises me a little bit, is the fact, that nobody else seems to have that problem. At least I did not find anything related in the forum.