fix: Prevent unsupported traffic classes to be set and cause crash

vsphere/distributed_virtual_switch_structure.go

@@ -642,6 +642,11 @@ func expandSliceOfDvsHostInfrastructureTrafficResource(d *schema.ResourceData) [
 // flattenSliceOfDvsHostInfrastructureTrafficResource reads in the supplied network I/O control allocation entries supplied via a respective DVSConfigInfo field and sets the appropriate keys in the supplied ResourceData.
 func flattenSliceOfDvsHostInfrastructureTrafficResource(d *schema.ResourceData, s []types.DvsHostInfrastructureTrafficResource) error {
 	for _, v := range s {
+		if !stringInSlice(v.Key, infrastructureTrafficClassValues) {
+			// this would imply there are new classes introduced by the vCenter
+			// API but not yet supported by govmomi/provider
+			continue
+		}
 		if err := flattenDvsHostInfrastructureTrafficResource(d, v, v.Key); err != nil {
 			return err
 		}

vsphere/util.go

@@ -0,0 +1,10 @@
+package vsphere
+
+func stringInSlice(s string, list []string) bool {
+	for _, i := range list {
+		if i == s {
+			return true
+		}
+	}
+	return false
+}

website/docs/r/distributed_virtual_switch.html.markdown

@@ -237,7 +237,7 @@ pools, if their use is so desired.
 
 #### Network I/O control traffic classes
 
-There are currently 9 traffic classes that can be used for network I/O
+There are currently 10 traffic classes that can be used for network I/O
 control - they are below.
 
 Each of these classes has 4 options that can be tuned that are discussed in the
@@ -254,6 +254,7 @@ next section.
 <tr><td>Virtual Machine Traffic</td><td>`virtualmachine`</td></tr>
 <tr><td>vMotion Traffic</td><td>`vmotion`</td></tr>
 <tr><td>VSAN Traffic</td><td>`vsan`</td></tr>
+<tr><td>Backup NFC</td><td>`backupnfc`</td></tr>
 </table>
 
 #### Traffic class resource options