[MWRAPPER-114] - Maven wrapper relative distributionUrl does not work…

[danishcake]

… on Windows

There is a Path -> URI -> Path roundtrip which was being incorrectly carried out. For Windows file URIs like

file:///C:/test

calling distUrl.getPath() resulted in /C:/test, which Paths.get could not handle. Existing behaviour is preserved for non-file URIs

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