code: public OperationFuture<List<FirewallPolicy>> delete(List<FirewallPolicy> firewallPolicyList) {
          List<JobFuture> jobs = firewallPolicyList
              .stream()
              .map(reference -> delete(reference).jobFuture())
              .collect(toList());
  
          return new OperationFuture<>(
              firewallPolicyList,
              new ParallelJobsFuture(jobs)
          );
      }
docs: Delete firewall policy list
  
  @param firewallPolicyList firewall policy list
  @return OperationFuture wrapper for firewall policy list