The following sample reassigns a task from a current assignee (user) to a different assignee.
//for this sample, it is assumed that a task record already exists with a unique key String equal to uniqueKey
protected TaskRepository taskRepository;
private test_reassign() throws Exception {
//reassign a task identified by its unique key to a new assignee, identified by his corresponding user unique key ("user_1005")
taskRepository.reassign(uniqueKey, "user_1005");
}