Do you use the SDK VMware-vSphere-SDK-5.1.0-774886 to develop a plugin? If so, you can see code under folder "VMware-vSphere-SDK-5.1.0-774886\SDK\vsphere-ws\java\JAXWS\samples\com\vmware\vm".
And VMCreate.java tells you how to create a new VM by programming. Hope it helps you.