vCloud Director - provider storage profile

I am having difficulty starting with the vcloud director API.

var host = vcdHost;
var adminHost = host.toAdminObject();
var providerVdcs = adminHost.getProviderVdcs();
foreach (var vdc in providerVdcs) {
if(vdc.id = "xxx") {
var providerVdc = vdc.toAdminExtensionObject();
}
}
var params = System.getModule("com.vmware.library.vCloud.schema.objects.extension").createUpdateProviderStorageProfilesParams(
Array("192.168.10.130"),
null,
null,
null
);
providerVdc.updateStorageProfiles(params, null);

However this results in a null pointer error.  Am I starting this in the right direction?