As reported in the comments in #5248, VMware host creation fails with:

Failed to create a compute SysEng-vCenter (VMWare) instance test9.lab2.lan: failed to create vm: undefined method `new' for "VirtualVmxnet3":String

Digging into it, the changes in #2438 to the create_vm + related methods has resulted in us sending a hash with keys as strings into Fog, so the interface type isn't correctly converted from a string into a class.