Fix typo (inverted test) that could lead to NPE

ludovicp

29.09.2008 074f9070e645d3e5935264e6f308a69b925c7f72

 opends/src/server/org/opends/server/api/Backend.java

@@ -381,7 +381,7 @@

        MatchingRule matchingRule;
        String matchingRuleID = filter.getMatchingRuleID();
        if (matchingRuleID == null)
        if (matchingRuleID != null)
        {
          matchingRule = DirectoryServer.getMatchingRule(
                              matchingRuleID.toLowerCase());