code: public static <T> Future<T> precomputed(final T value) {
          return new Future<T>() {
              public boolean cancel(boolean mayInterruptIfRunning) {
                  return false;
              }
  
              public boolean isCancelled() {
                  return false;
              }
  
              public boolean isDone() {
                  return true;
              }
  
              public T get() {
                  return value;
              }
  
              public T get(long timeout, TimeUnit unit) {
                  return value;
              }
          };
      }
docs: Creates a {@link Future} instance that already has its value pre-computed.