Plus sign in Mediawiki links is converted to underscore

Use Case: using the MediaWiki XML Input stream and the xwiki+instance output stream to import MediaWiki pages into XWiki via the Filter Application.

If a page contains a {} sign, then in links to this page the {} is converted to an _ . The page itself is created in XWiki with the plus in place.

E.g. a MediaWiki link

[[Page A+B]]
{{code}}

is converter to an XWiki link:

[[MW-Import.Page_A_B.WebHome]]

while the page is actually stored at {{MW-Import.Page_A+B.WebHome}}

Also MediaWiki is quite tolerant whn it comes to whitespace in a link. E.g.:

[[Page __ __ Page]]

is a valid link to the page Page_Page. This gets imported as a link to Page__________Page into XWiki, however.

Ok, I am mixing two things up here, but I discovered both at nearly the same time in the same migration, so I am going to provide a simple for both.