How to call RefreshIndicator from code?

Question

Android

How to call RefreshIndicator from code on startup or button click?
I am using Provider to manage application state

@override
  Widget build(BuildContext context) {
    context.read<Data>().httpRequest();

    return RefreshIndicator(
      onRefresh: () {
        return context.read<Data>().httpRequest();
      },
      child: Column(
        children: [
          DropdownButton<int>(
            hint: Hint(),
            items: loansServicecList(context),
            onChanged: (int value) {
              if (value != context.read<Data>().i) {
                context.read<Data>().i = value;
                context.read<Data>().httpRequest();
              }
            },
          ),
          Flexible(
            child: ServicesList(),
          ),
        ],
      ),
    );
  }

the httpRequest() method loads the data, but the RefreshIndicator naturally does not work in this situation