metro is ambiguous and has to go, or you'll keep getting questions accidentally tagged to it.
I would suggest to use metro-web or metro-web-java or metro-java instead:
metro-web makes the user more likely to read what it is, but accidental tags could still happen.
metro-web-java is as verbose as it can gets, no way that you can misunderstand that.
metro-java could work as well, since the
web
notion might not be necessary.
Don't add framework
because it adds no value to the tag name.
So, here's the approach I would suggest:
Contact the sponsor that he is sponsoring the wrong tag.
Sort out metro to only contain Java Metro-related questions, metro-ui for the design language.
Move all questions from metro to metro-web-java or metro-java.
Call Trogdor using the awesome sign and ask him to burninate metro (and blacklist it).
???
Profit! Everybody happy...
Here is an image explaining it all with tags, SE team, sponsor(s), freehand circles, unicorns and Trogdor:
Any resemblance with real-life persons, drakes or unicorns is purely coincidentally...