[ovirt-users] assign hostname to vm using REST API

I am using REST API to integrate rhev with java(not SDK) I am trying to assign hostname to vm but showing some bad request error. I have created template from vm which have cloud init package in it also m using rhev 3.4. Do i need to use payload method if so please provide me the proper code for both -for passing payload through code in url and the payload file sample can anyone plz tell me how to do it?