Method result.hasMoreElement() has not to be called two times, if the first call returns false.
With some LDAP, this method could return false at first call and true at second call.

Thne, the algorithm of methods like getUser(String login) must be corrected as bellow :

results = doSearch()

if (results.hasMoreElements())
{
[...]
if (results.hasMoreElements())

{ getLogger().error([..]); }

}

instead:

results = doSearch()

if (results.hasMoreElements())

{ [...] }

if (results.hasMoreElements())

{ getLogger().error([..]); }