if (resolver == null) { return;
if (resolver == null) { return; }  String key = _dnsserver.toString(); if (resolvers.containsKey(key)) { org.xbill.DNS.Resolver resolv = (org.xbill.DNS.Resolver) resolvers .remove(key);  if (resolver.getResolvers().length == 1) { resolver = null; } else { resolver.deleteResolver(resolv); } }
  public static void removeDnsServer(ProtocolAddress _dnsserver)  {    if (resolver == null)    {      return;    }    String key = _dnsserver.toString();    if (resolvers.containsKey(key))    {      org.xbill.DNS.Resolver resolv = (org.xbill.DNS.Resolver) resolvers.remove(key);      if (resolver.getResolvers().length == 1)        resolver = null;      else        resolver.deleteResolver(resolv);    }  }