I have m2e installed in Eclipse and global maven configured in it. Recently I have added two geottools repositories, but Eclipse does not show them:

Also it is not finding artefacts from it, like gt-shapefile.
How to force indexing? Rebuild Index and Update Index did not help. Removing m2e plugin folders from .metadata workspace folder also didn't help.
Go to Preferences > Maven
and select Download repository index updates on startup check box
Restarting eclipse should trigger index download for each repository. Also note that Repository should provide an index in first place for this option to work.
Please see error log ( Window > Show View ) for any related messages.