On 03/02/2014 08:32 PM, Michiel Hobbelman wrote:
  When using group name "A & B"  it
is impossible to set permissions in the
 WebPreferences.
 Xwiki version 5.4.1.
 Is this a bug?
 ( maybe related to 
http://jira.xwiki.org/browse/XWIKI-5448  ?)
 Regards,
 Michiel 
 Yes, it is a bug, but an unrelated one.
 The same problem exists in the wiki admin.
 The name of the group is not properly encoded.
 Can you please create a new issue in jira? 
Never mind about, I found the problem and it should be fixed in the next release: