@Override
    public Collection<User> findUsers(Set<String> fields, String query)
            throws UnsupportedOperationException
    {
        return findUsers(fields, query, -1, -1);
    }
LDAP implementation of the UserProvider interface. All data in the directory is
treated as read-only so any set operations will result in an exception.

@author Matt Tucker
xmppserver/src/main/java/org/jivesoftware/openfire/ldap/LdapUserProvider.java