docs: public LatchedLazyFuture<X> withRunningThread() {
          if (state.get() == DONE) return this;
          if (state.compareAndSet(null, STARTED)) {
              Thread thread = new Thread(this.getClass().getName() + ".withRunningThread") {
                  @Override
                  public void run() {
                      try {
                          internalCalc();
                      } catch (ExecutionException | InterruptedException e) {
                          e.printStackTrace();
                      }
                  }
              };
              thread.start();
  
              return this;
          } else {
              return this;
          }
      }