Thanks Ralph for help and Rahul for asking question!

  I found this code working to create workitems using templates.
Method call "instantiateTemplate" basically creates WI using process templates

IWorkItemTemplateClient witc = (IWorkItemTemplateClient) repository.getClientLibrary(IWorkItemTemplateClient.class);
        String projectAreaName = "Project name;
        IProcessClientService processClient = (IProcessClientService) repository
        .getClientLibrary(IProcessClientService.class);
        URI uri = URI.create(projectAreaName .replaceAll(" ", "%20"));
        IProjectArea projectAreaHandle = (IProjectArea) processClient.findProcessArea(uri, null, null);
        System.out.println(projectAreaHandle.getName());
        List<IWorkItemTemplateHandle> templateHandles = witc.getTemplateHandles(projectAreaHandle, monitor);
        for(IWorkItemTemplateHandle templateHandle : templateHandles){
            if(templateHandle.getName().equals("Epic Template")){
                System.out.println("Name===="+templateHandle.getName());
                Map<IAttributeVariable, Object> map = new HashMap<IAttributeVariable, Object>();
                int[] count = witc.instantiateTemplate(templateHandle, map, monitor);
            }
        }

Rabul,

looking at the Eclipse client you can see where this is done in the Client SDK:


If you go into the code, you can see this code:



I am not sure if IWorkItemTemplateClient is in the plain JavaClient Libraries, but it is the class that is used in the RTC Eclipse client.