VcHostFirewallRuleDirection Object Creation

I am trying to create a new ESXi host firewall rule and am trying to define a VcHostFirewallRuleDirection object by using the following:

var firewallRuleDirection = new VcHostFirewallRuleDirection();

I receive the following error: 

 Unable to create object : VcHostFirewallRuleDirection : com.vmware.vim.binding.vim.host.Ruleset$Rule$Direction

Seems pretty simple, but it's def. not correct for some reason.  What would be the correct syntax to create this?