Improved toString to use our best practice (and make it clear it's a "debug"...

Improved toString to use our best practice (and make it clear it's a "debug" method - was ambiguous before).

git-svn-id: https://svn.xwiki.org/svnroot/xwiki/platform/core/trunk@20731 f329d543-caf0-0310-9063-dda96c69346f