Use the CreateWorkItem request to create a new Work Item in a Polarion project.
PolarionClient client = PolarionClient.createClient(serverUri, username, password);
URI creationFactory = new GetServiceProviderCatalog(client).call()
.getServiceProvider(projectId)
.getCreationFactory(Polarion.TYPE_WORKITEM)
.getCreation();
WorkItem workItem = new WorkItem();
workItem.setTitle("My new requirement");
workItem.setDescription("Description of the requirement");
URI createdUri = new CreateWorkItem(client, creationFactory, workItem).call();