public Principal authenticate(String username,
                                  Object credentials,
                                  HttpRequest request)
    {
        KnownUser user;
        synchronized (this)
        {
            user = (KnownUser)super.get(username);
        }
        if (user==null)
            return null;

        if (user.authenticate(credentials))
            return user;
        
        return null;
    }
public Principal authenticate ( String username , Object credentials , HttpRequest request ) { KnownUser user ; synchronized ( this ) { user = ( KnownUser ) super . get ( username ) ; } if ( user == null ) return null ; if ( user . authenticate ( credentials ) ) return user ; return null ; }
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