code: public final void setWork(final long work) {
      if (getWork() != WORK_UNKNOWN) {
        throw new IllegalStateException("Cannot set work amount if it was already previously specified");
      }
      new JAtomic() {
        @Override boolean abort(Job job) { return false; }
        @Override void update(Job old) { old._work = work; }
      }.apply(this);
    }
docs: Set the amount of work for this job - can only be called if job was started without work specification