code: public OperationFuture<List<FirewallPolicy>> delete(FirewallPolicyFilter filter) {
          return delete(
              findLazy(filter)
                  .map(metadata -> FirewallPolicy.refById(
                      metadata.getId(),
                      DataCenter.refById(metadata.getDataCenterId()))
                  )
                  .collect(toList())
          );
      }
docs: Delete filtered firewall policy
  
  @param filter firewall policy filter
  @return OperationFuture wrapper for firewall policy list