public Closure join() throws InterruptedException {
        final JoinableClosure joinable = castToJoinalbe(this.done);
        joinable.join();
        return joinable.getClosure();
    }
Waiting for the task to complete, to note that throughput may be reduced,
which is generally not recommended.

@return done closure
@throws InterruptedException if the current thread is interrupted while waiting
@since 1.3.1
jraft-core/src/main/java/com/alipay/sofa/jraft/entity/Task.java