CREATE TABLE IF NOT EXISTS `db`.`Task` (
  `id` BIGINT NOT NULL AUTO_INCREMENT,
  PRIMARY KEY (`id`),
  ENGINE = InnoDB
DEFAULT CHARACTER SET = utf8
COLLATE = utf8_general_ci;

CREATE TABLE IF NOT EXISTS `db`.`TaskResult` (
  `id` BIGINT NOT NULL AUTO_INCREMENT,
  `task` BIGINT NOT NULL,
  PRIMARY KEY (`id`),
  INDEX `fk_TaskResult_Task1_idx` (`task` ASC),
  CONSTRAINT `fk_TaskResult_Task1`
    FOREIGN KEY (`task`)
    REFERENCES `db`.`Task` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  ENGINE = InnoDB
DEFAULT CHARACTER SET = utf8
COLLATE = utf8_general_ci;

...
Task task = (Task) s.get(Task.class, 1l);
if (null != task) {
    TaskResult result = new TaskResult();

    result.setTask(task);
    session.save(result);

    session.getTransaction().commit();
}
...