How to import external java classes in SoapUI 5.0.0 ?

I am trying to import some external java classes in my groovy script. All these classes are located under "C:\Program Files (x86)\SmartBear\SoapUI-5.0.0\bin\ext\DDDD" folder.

I am getting an error "unable to resolve class ITDConnection@ line 4, column 15 ITDConnection itdc= ClassFactory.createTDConnection()" for below code

import com4j.*;
import DDDD.*;

ITDConnection itdc = ClassFactory.createTDConnection()
itdc.initConnectionEx(url)