We only use distributed vswitches in our vmware environment, and the plugin seems to break when we try to add or change a network interface on a VM.
The error message is
com.vmware.vim25.virtualethernetcarddistributedvirtualportbackinginfo cannot be cast to com.vmware.vim25.virtualethernetcardnetworkbackinginfo

Unfortunately I am no java expert, but the error seems to originate from ReconfigureNetworkAdapters.java which only seems to handle virtualethernetcardnetworkbackinginfo.

When we manually set the network on the VM in vSphere client, we see the network name (vm-<vlanid>) with the type "Distributed Port Group". Unfortunately our VMware support dept will not allow us to use "regular" vswitches on a standard port group.