Cannot Retrieve OAuth Request Token

[iovan4o]

I run josm-tested version 3208,
I go to Preferences->Connection Settings->Authentication, select "Use OAuth" and click the "Authorize now" button. In the "Get an Access Token..." dialog I select Semi-automatic procedure. After I click "Retrieve Request Token" button an error dialog appears with the following message:
Retrieving an OAuth Request Token from '​http://www.openstreetmap.org/oauth/request_token' failed.
In the console there is the following exception:

org.openstreetmap.josm.gui.oauth.OsmOAuthAuthorizationException: oauth.signpost.exception.OAuthNotAuthorizedException:
Authorization failed (server replied with a 401). This can happen if the consumer key was not correct or the signatures did not match.
        at org.openstreetmap.josm.gui.oauth.OsmOAuthAuthorizationClient.getRequestToken(OsmOAuthAuthorizationClient.java:141)
        at org.openstreetmap.josm.gui.oauth.RetrieveRequestTokenTask.realRun(RetrieveRequestTokenTask.java:79)
        at org.openstreetmap.josm.gui.PleaseWaitRunnable.doRealRun(PleaseWaitRunnable.java:83)
        at org.openstreetmap.josm.gui.PleaseWaitRunnable.run(PleaseWaitRunnable.java:129)
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
        at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
        at java.util.concurrent.FutureTask.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)
Caused by: oauth.signpost.exception.OAuthNotAuthorizedException: Authorization failed (server replied with a 401).
This can happen if the consumer key was not correct or the signatures did not match.
        at oauth.signpost.basic.DefaultOAuthProvider.retrieveToken(DefaultOAuthProvider.java:143)
        at oauth.signpost.basic.DefaultOAuthProvider.retrieveRequestToken(DefaultOAuthProvider.java:79)
        at org.openstreetmap.josm.gui.oauth.OsmOAuthAuthorizationClient.getRequestToken(OsmOAuthAuthorizationClient.java:132)
        ... 9 more

Regards,
Ivan