code: public Operation setMachineType(MachineTypeId machineType, OperationOption... options) {
      return compute.setMachineType(getInstanceId(), machineType, options);
    }
docs: Sets the machine type for this instance. The instance must be in {@link
  InstanceInfo.Status#TERMINATED} state to be able to set its machine type.
  
  @return a zone operation if the set request was issued correctly, {@code null} if the instance
  was not found
  @throws ComputeException upon failure