docs: @Override
      protected <T> CompletableFuture<T> doExecute(Command<T> command) throws Exception {
          final CompletableFuture<T> future = new CompletableFuture<>();
          executor.execute(() -> {
              try {
                  future.complete(blockingExecute(command));
              } catch (Throwable t) {
                  future.completeExceptionally(t);
              }
          });
          return future;
      }