code: @Override
      public CompletableFuture<T> newIncompleteFuture() {
          if (JAVA8)
              return new ManagedCompletionStage<T>(new CompletableFuture<T>(), defaultExecutor, null);
          else
              return new ManagedCompletionStage<T>(defaultExecutor);
      }
docs: minimalCompletionStage is allowed because java.util.concurrent.CompletableFuture's minimalCompletionStage allows it