When you make a dumb slave using Java Web Start, you get a command to start the slave from the command line in the slave overview page. This command contains a part "-secret <HEXSTRING>".

When creating a vsphere slave with java webstart as secondary start option, there is no way to retrieve the secret to use to get the slave started, unless I missed something.

The only work around for now seems to create the slave first as a dumb slave, then write down the secret, drop the slave and recreate it as a vsphere slave with the same name, as it seems the secret is determined by the name. This seems a strange way of doing things and introduces double work.