add note on vmwarweguru->getCommandHostDelegation

plugins/hypervisors/vmware/src/com/cloud/hypervisor/guru/VMwareGuru.java

@@ -300,6 +300,8 @@ public class VMwareGuru extends HypervisorGuruBase implements HypervisorGuru {
     public Pair<Boolean, Long> getCommandHostDelegation(long hostId, Command cmd) {
         boolean needDelegation = false;
 
+        //NOTE: the hostid can be a hypervisor host, or a ssvm agent. For copycommand, if it's for volume upload, the hypervisor
+        //type is empty, so we need to check the format of volume at first.
         if (cmd instanceof CopyCommand) {
             CopyCommand cpyCommand = (CopyCommand)cmd;
             DataTO srcData = cpyCommand.getSrcTO();